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BIOLOGY 
UBRAPV 


THE    MICROSCOPIST. 


ZENTMAYER'S  LARGEST  MICROSCOPE. 

•  ONE-THIRD  ACTUAL  SIZE. 


THE 


MICROSCOPIST 


MANUAL  OF  MICROSCOPY 

AND 

COMPENDIUM  OF  THE  MICROSCOPIC   SCIENCES, 

MICRO-MINERALOGY,    MICRO-CHEMISTRY,    BIOLOGY,    HISTOLOGY, 
AND     PATHOLOGICAL     HISTOLOGY. 

THIRD  EDITION. 
KEWKITTEN  AND  GEEATLY  ENLAKGED. 

WITH 

TWO    HUNDRED    AND    FIVE    ILLUSTRATIONS. 


J.    H.    WYTHE,  A.M.,  M.D., 

PROFESSOR   OF   MICROSCOPY  AND   BIOLOGY   IN    THE   MEDICAL   COLLEGE   OF   THE   PACIFIC, 
SAN    FRANCISCO. 


PHILADELPHIA: 
LINDSAY    &    BLAKISTON. 

1877. 


BIOLOGY 
UVRARY 


Entered  according  to  Act  of  Congress,  in  the  year  1877, 

By   LINDSAY    &   BLAKISTON, 
In  the  office  of  the  Librarian  of  Congress  at  Washington,  D.  C. 

/  3. 


PHILADELPHIA: 
SHERMAN  &  CO.,  PRINTERS. 


RESPECTFULLY    DEDICATED 

TO    THE     - 

SAN  FRANCISCO  MICROSCOPICAL  SOCIETY, 

AS   A   TESTIMONY 

TO    THE 

ZEAL   AND    INDUSTRY    OF    ITS    MEMBERS 
IN  THE    PROSECUTION 

OF 

MICROSCOPIC     SCIENCE. 


PREFACE. 


THE  progress  of  microscopic  science  may  be  well  illus- 
trated by  a  comparison  between  the  present  and  former 
editions  of  this  book.  The  author's  intention  was  to 
place  within  the  reach  of  the  student  of  nature  a  com- 
pendium of  microscopy,  free  from  unnecessary  verbiage, 
which  should  aid  in  every  department  of  natural  science. 
It  is  110  small  compliment  to  such  a  work  that  for  a 
quarter  of  a  century  it  should  hold  a  place  among  works 
of  reference,  although  surrounded  by  larger  and  more 
pretentious  volumes.  In  order  to  meet  the  request  of 
the  publishers  for  another  edition,  it  has  been  found 
necessary  to  rewrite  the  entire  book,  and  although  the 
original  design  has  been  kept  in  view,  the  numerous 
additions  to  our  science  render  considerable  enlargement 
needful,  notwithstanding  the  effort  made  to  concentrate 
the  material  into  the  smallest  compass  consistent  with 
perspicuity. 

The  vision  of  microscopy  sweeps  over  all  the  world, 
and  embraces  all  forms  of  organic  and  inorganic  ex- 


Vlll  PREFACE. 

istence.  To  give  directions  respecting  most  approved 
methods,  and  to  classify  the  most  important  facts,  has 
required  labor,  which  it  is  hoped  will  result  in  rendering 
the  work  a  necessary  companion  to  the  student,  and  an 
aid  to  the  progress  of  real  science. 

Many  of  the  figures  illustrating  the  lower  forms  of  life, 
and  normal  and  pathological  histology,  have  been  drawn 
from  the  works  of  Carpenter,  Beale,  Frey,  Strieker,  Bill- 
roth,  and  Rindfleisch,  to  which  the  more  advanced  stu- 
dent is  referred  for  further  details. 

January,  1877. 


CONTENTS. 


CHAPTER  I. 
HISTORY  AND  IMPORTANCE  or  MICROSCOPY. 

Application  of  the  Microscope  to  Science  and  Art — Progress  of  Micros- 
copy,    .  .  17-21 

CHAPTER  II. 
THE  MICROSCOPE. 

The  Simple  Microscope — Chromatic  and  Spherical  Aberration— Com- 
pound Microscope  —  Achromatic  Object-glasses  —  Eye-pieces  —  Me- 
chanical Arrangements — Binocular  Microscope,  .  .  .  21-32 

CHAPTER  III. 

MICROSCOPIC  ACCESSORIES. 

Diaphragms — Condensers — Oblique  Illuminators — Dark-ground  ditto — 
Illumination  of  Opaque  Objects — Measuring  and  Drawing  Objects — 
Standards  of  Measurement — Moist  Chamber — Gas  Chamber — Warm 
Stage — Polari  scope — Microspectroscope — Nose-piece — Object-finders 
— Micro-photography,  ........  32-48 

CHAPTER  IV. 

USE  OP  THE  MICROSCOPE. 

Care  of  the  Instrument — Care  of  the  Eyes— Table— Light— Adjustments 
— Errors  of  Interpretation — Testing  the  Microscope,  .  .  48-58 

B 


X  CONTENTS. 

CHAPTER  V. 

MODERN  METHODS  OF  EXAMINATION. 

Preliminary  Preparation  of  Objects— Minute  Dissection— Preparation 
of  Loose  Textures— Preparation  by  Teasing— Preparation  by  Section 
—Staining  Tissues— Injecting  Tissues— Preparation  in  Vi>cid  Media 
—Fluid  Media— Indifferent  Fluids— Chemical  Reagents— Staining 
Fluids Injecting  Fluids — Preservative  Fluids— Cements,  .  58-76 

CHAPTER  VI. 

MOUNTING  AND  PRESERVING  MICROSCOPIC  OBJECTS. 

Opaque  Objects— Cells — Dry  Objects — Mounting  in  Balsam  or  Dammar — 
Mounting  in  Fluid — Cabinets — Collecting  Objects — Aquaria,  76-83 

CHAPTER  VII. 

THE  MICROSCOPE  IN  MINERALOGY  AND  GEOLOGY. 

Preparation  of  Specimens  —  Examination  of  Specimens  —  Crystalline 
Forms — Crystals  witbin  Crystals— Cavities  in  Crystals — Use  of  Po- 
larized Light — Origin  of  Rock  Specimens — Materials  of  Organic 
Origin — Microscopic  Paleontology,  .....  84-98 

CHAPTER  VIII. 
THE  MICROSCOPE  IN  CHEMISTRY. 

Apparatus  and  Modes  of  Investigation — Preparation  of  Crystals  for  the 
Polariscope — Use  of  the  Microspectroscope — Inverted  Microscope — 
General  Micro-chemical  Tests — Determination  of  Substances — Al- 
kalies— Acids — Metallic  Oxides — Alkaloids — Crystalline  Forms  of 
Salts, 98-115 

CHAPTER  IX. 

THE  MICROSCOPE  IN  BIOLOGY. 

Theories  of  Life — Elementary  Unitor  Cell — Cell-structureand  Formation 
— Phenomena  of  Bioplasm — Movements  of  Cells — Microscopic  Dem- 
onstration of  Bioplasm — Chemistry  of  Cells  and  their  Products — Va- 
rieties of  Bioplasm — Cell-genesis — Reproduction  in  Higher  Organ- 
isms— Alternation  of  Generations — Parthenogenesis  —Transforma- 
tion and  Metamorphosis — Discrimination  of  Living  Forms,  116-127 


CONTENTS.  xi 

CHAPTER  X. 

THE  MICROSCOPE  IN  VEGETABLE  HISTOLOGY  AND  BOTANY. 

Molecular  Coalescence — Cell-substance  in  Vegetables — Cell- wall  or  Mem- 
brane— Ligneous  Tissue— Spiral  Vessels — Laticiferous  Vessels — Si- 
liceous Structures — Formed  Material  in  Cells — Forms  of  Vegetable 
Cells — Botanical  Arrangement  of  Plants — Fungi — Protopbytes — 
Desmids  —  Diatoms  —  Nostoc  —  Oscillatoria  —  Examination  of  the 
Higher  Cryptogamia — Examination  of  Higher  Plants,  .  128-157 

CHAPTER  XI. 
THE  MICROSCOPE  IN  ZOOLOGY. 

Monera  —  Rhizopods  —  Infusoria — Rotatoria — Polyps — Hydroids — Aca- 
lephs  —  Echinoderms  —  Bryozoa — Tunicata  —  Conchifera — Gastero- 
poda —  Cephalopoda  —  Entozoa  —  Annulata  —  Crustacea — Insects  — 
Arachnida — Classification  of  the  Invertebrata,  .  .  .  158-182 

CHAPTER  XII. 

THE  MICROSCOPE  IN  ANIMAL  HISTOLOGY. 

Histo-chemistry  —  Histological  Structure  —  Simple  Tissues  —  Blood  — 
Lymph  and  Chyle — Mucus — Epithelium — Hair  and  Nails — Enamel 
— Connective  Tissues — Compound  Tissues — Muscle — Nerve — Glan- 
dular and  Vascular  Tissue— Development  of  the  Tissues — Digestive 
and  Circulatory  Organs — Secretive  Organs — Respiratory  Organs — 
Generative  Organs — Locomotive  Organs — Sensory  Organs — Organs 
of  Special  Sense — Suggestions  for  Practice,  .  .  .  182-226 

CHAPTER  XIII. 

THE  MICROSCOPE  IN  PRACTICAL  MEDICINE  AND  PATHOLOGY. 

Microscopic  Appearances  after  Death  of  the  Tissues — Morbid  Action  in 
Tissues — New  Formations  —  Examination  of  Urinary  Deposits — 
Human  Parasites— Examination  of  Sputa— Microscopic  Hints  in 
Materia  Medica  and  Pharmacy,  .....  226-245 


1 1 B  R  A  R  Y 

NIVERSITY  OF 


THE  MICROSCOPIST. 


CHAPTER    I. 

HISTORY    AND   IMPORTANCE    OF    MICROSCOPY. 

THE  term  microscopy,  meaning  the  use  of  the  micro- 
scope, is  also  applied  to  the  knowledge  obtained  by  this 
instrument,  and  in  this  sense  is  commensurate  with  a 
knowledge  of  the  minute  structure  of  the  universe,  so  far 
as  it  may  come  under  human  observation.  Physics  and 
astronomy  treat  of  the  general  arrangement  and  motions 
of  masses  of  matter,  chemistry  investigates  their  constitu- 
tion, and  microscopy  determines  their  minute  structure. 
The  science  of  histology,  so  important  to  anatomy  and 
physiology,  is  wholly  the  product  of  microscopy,  while 
this  latter  subject  lends  its  aid  to  almost  every  other 
branch  of  natural  science. 

To  the  student  of  physical  phenomena  this  subject  un- 
folds an  amazing  variety  developed  from  most  simple 
beginnings,  while  to  the  Christian  philosopher  it  gives  the 
clearest  evidence  of  that  Creative  Power  and  Wisdom 
before  whom  great  and  small  are  terms  without  meaning. 

In  the  arts,  as  well  as  in  scientific  investigations,  the 
microscope  is  used  for  the  examination  and  preparation  of 
delicate  wrork.  The  jeweller,  the  engraver,  and  the  miner 
find  a  simple  microscope  almost  essential  to  their  employ- 
ments. This  application  of  the  magnifying  power  of  lenses 
was  known  to  the  ancients,  as  is  shown  by  the  glass  lens 

2 


18  THE    MICROSCOPIST. 

found  at  Nineveh,  and  by  the  numerous  gems  and  tablets 
so  finely  engraved  as  to  need  a  magnifying  glass  to  detect 
their  details. 

In  commerce,  the  microscope  has  been  used  to  detect 
adulterations  in  articles  of  food,  drugs,  and  manufactures. 
In  a  single  year  $60,000  worth  of  adulterated  drugs  was 
condemned  by  the  New  York  inspector,  and,  so  long  as 
selfishness  is  an  attribute  of  degraded  humanity,  so  long 
will  the  microscope  be  needed  in  this  department. 

In  agriculture  and  horticulture  microscopy  affords  valu- 
able assistance.  It  has  shown  us  that  mildew  and  rust  in 
wheat  and  other  food-grains,  the  "  potato  disease,"  and 
the  "vine  disease,"  are  dependent  on  the  growth  of  minute 
parasitic  fungi.  It  has  also  revealed  many  of  the  minute 
insects  which  prey  upon  our  grain-bearing  plants  and  fruit 
trees.  The  damage  wrought  by  these  insects  in  the  United 
States  alone  has  been  estimated  by  competent  observers 
as  not  less  than  three  hundred  millions  of  dollars  in  each 
year.  The  muscardine,  which  destroys  such  large  num- 
bers of  silk-worms  in  France  and  other  places,  is  caused 
by  a  microscopic  fungus,  the  Botrytis  bassiana. 

The  mineralogist  determines  the  character  of  minute 
specimens  or  of  thin  sections  of  rock,  and  the  geologist 
finds  the  nature  of  many  fossil  remains  by  their  magnified 
image  in  the  microscope. 

The  chemist  recognizes  with  this  instrument  excessively 
minute  quantities  and  reactions  which  would  otherwise 
escape  observation.  Dr.  Wormley  shows  that  micro- 
chemical  analysis  detects  the  reaction  of  the  10,000th  to 
the  100,000th  part  of  a  grain  of  hydrocyanic  acid,  mer- 
cury, or  arsenic,  and  very  minute  quantities  of  the  vege- 
table alkaloids  may  be  known  by  a  magnified  view  of  their 
sublimates.  The  micro-spectroscope  promises  still  more 
wonderful  powers  of  analysis  by  the  investigation  of  the 
absorption  bands  in  the  spectra  of  different  substances. 

In  biology  the  wonderful  powers  of  the  microscope  find 


HISTORY    AND    IMPORTANCE    OF    MICROSCOPY.          19 

their  widest  range.  If  we  see  not  life  itself,  we  see  its 
first  beginnings,  and  the  process  of  its  development  or 
manifestation.  If  we  see  not  Nature  in  her  undress,  we 
trace  the  elementary  warp  and  woof  of  her  mystic  drapery. 

In  vegetable  and  animal  physiology  we  see,  by  its 
means,  not  only  the  elementary  unit — the  foundation-stone 
of  the  building — but  also  chambers  and  laboratories  in 
the  animated  temple,  which  we  should  never  have  sus- 
pected— tissues  and  structures  not  otherwise  discoverable 
— not  to  speak  of  species  innumerable  which  are  invisible 
to  the  naked  eye. 

In  medical  science  and  jurisprudence  the  contributions 
of  microscopy  have  been  so  numerous  that  constant  study 
in  this  department  is  needed  by  the  physician  who  would 
excel  or  even  keep  pace  with  the  progress  of  his  profes- 
sion. Microscopy  may  be  truly  called  the  guiding  genius 
of  medical  science. 

Even  theology  has  its  contribution  from  microscopy. 
The  teleological  view  of  nature,  which  traces  design,  re- 
ceives from  it  a  multitude  of  illustrations.  In  this  de- 
partment the  war  between  skeptical  philosophy  and  theol- 
ogy has  waged  most  fiercely;  and  if  the  difference  between 
living  and  non-living  matter  may  be  demonstrated  by  the 
microscope,  as  argued  by  Dr.  Beale  and  others,  theology 
sends  forth  a  paean  of  victory  from  the  battlements  of  this 
science. 

The  attempts  made  by  early  microscopists  to  determine 
ultimate  structure  were  of  but  little  value  from  the  im- 
perfections of  the  instruments  employed,  the  natural  mis- 
takes made  in  judging  the  novel  appearances  presented, 
and  the  treatment  to  which  preparations  were  subjected. 
In  late  years  the  optical  and  mechanical  improvements  in 
microscopes  have  removed  one  source  of  error,  but  other 
sources  still  remain,  rendering  careful  attention  to  details 
and  accurate  judgment  of  phenomena  quite  essential.  Care- 
ful manipulation  and  minute  dissection  require  a  knowledge 


20  *  THE    MICROSCOPIST. 

of  the  effects  of  various  physical  and  chemical  agencies,  a 
steady  hand,  and  a  quick-discerning  eye.  Above  all, 
microscopy  requires  a  cultured  mind,  capable  of  readily 
detecting  sources  of  fallacy,  and  such  a  love  of  truth  as 
enables  a  man  to  free  himself  from  all  preconceived  no- 
tions of  structure  and  from  all  bias  in  favor  of  particular 
theories  and  analogies.  What  result  is  it  possible  to  draw 
from  the  observations  of  those  who  boil,  roast,  macerate, 
putrefy,  triturate,  and  otherwise  injure  delicate  tissues, 
except  for  the  purpose  of  isolating  special  structures  or 
learning  the  effects  of  such  agencies  ?  Yet  many  of  the 
phenomena  resulting  from  such  measures  have  been  de- 
scribed as  primary,  and  theories  of  development  have  been 
proposed  on  the  basis  of  such  imperfect  knowledge. 

Borelli  (1608-1656)  is  considered  to  be  the  tirst  who 
applied  the  microscope  to  the  examination  of  animal 
structure.  Malpighi  (1661)  first  witnessed  the  actual  cir- 
.culation  of  the  blood,  which  demonstrated  the  truth  of 
Harvey's  reasoning.  He  also  made  manj^  accurate  obser- 
vations in  minute  anatomy.  Lewenhoeck,  Swammerdam, 
Lyonet,  Lieberkuhn,  Hewson,  and  others,  labored  also  in 
this  department.  When  we  remember  that  these  early 
laborers  u^ed  only  simple  microscopes,  generally  of  their 
own  construction,  we  must  admire  their  patient  industry, 
skilful  manipulation,  and  accurate  judgment.  In  these 
respects  they  are  models  to  all  microscopists. 

Within  the  last  quarter  of  a  century  microscopic  ob- 
servers may  be  numbered  by  thousands,  and  some  have 
attained  an  eminent  reputation.  At  the  present  day,  in 
Germany,  England,  France,  and  the  United  States,  the 
most  careful  and  elaborate  investigations  are  being  made, 
older  observations  are  repeated  and  corrected,  new  discov- 
eries are  rapidly  announced,  and  the  most  hidden  recesses 
of  nature  are  being  explored. 

It  is  proposed  in  this  treatise  to  give  such  a  resume  of 
microscopy  as  shall  enable  the  student  in  any  department 


THE    MICROSCOPE.  21 

to  pursue  original  investigations  with  a  general  knowl- 
edge of  what  has  been  accomplished  by  others.  To  this 
end  a  comprehensive  view  of  the  necessary  instruments 
and  details  of  the  art,  or  what  the  Germans  call  technol- 
ogy, is  first  given,  and  then  a  brief  account  of  the  appli- 
cation of  the  microscope  to  various  branches  of  science, 
especially  considering  the  needs  of  physicians  and  stu- 
dents of  medicine. 


CHAPTER   II. 


THE    MICROSCOPE. 


The  Simple  Microscope. — The  magnifying  power  of  a 
glass  lens  (from  lens,  a  lentil ;  because  made  in  the  shape 
of  its  seeds)  was  doubtless  known  to  the  ancients,  but  only 
in  modern  times  has  it  been  applied  in  scientific  research. 

The  forms  of  lenses  generally  used  are  the  double  convex, 
with  two  convex  faces ;  piano  convex,  with  one  face  flat 
and  the  other  convex ;  double  concave,  with  two  concave 
faces ;  plajio-concave,  with  one  flat  and  one  concave  face  ; 
and  the  meniscus,  with  a  concave  and  a  convex  face. 

In  the  early  part  of  the  seventeenth  century  very  mi- 
nute lenses  were  used,  and  even  small  spherules  of  glass. 
Many  of  the  great  discoveries  of  that  period  were  made 
by  these  means.  A  narrow  strip  of  glass  was  softened  in 
the  flame  of  a  spirit-lamp  and  drawn  to  a  thread,  on  the 
end  of  which  a  globule  wras  melted  and  placed  in  a  thin 
folded  plate  of  brass,  perforated  so  as  to  admit  the  light. 
Some  of  these  globules  were  so  small  as  to  magnify  sev- 
eral hundred  diameters.  Of  course,  they  were  inconve- 
nient to  use,  and  larger  lenses,  ground  on  a  proper  tool, 
were  more  common. 

The  magnifying  power  of  lenses  depends  on  a  few  simple 


22  THE    MICROSCOPIST. 

optical  laws,  concerning  refraction  of  light,  allowing  the 
eye  to  see  an  object  under  a  larger  visual  angle  ;  so  that 
the  power  of  a  simple  microscope  is  in  proportion  to  the 
shortness  of  its  focal  length,  or  the  distance  from  the  lens 
to  the  point  where  a  distinct  image  of  the  object  is  seen. 
This  distance  may  be  measured  by  directly  magnifying 
an  object  with  the  lens,  if  it  be  a  small  one,  or  by  casting 
an  image  of  a  distant  window,  candle,  etc.,  upon  a  paper 
or  wall.  The  focus  of  the  lens  is  the  point  where  the 
image  is  most  distinct.  Different  persons  see  objects 
naturally  at  different  distances,  but  ten  inches  is  consid- 
ered the  average  distance  for  the  minimum  of  distinct 
vision.  A  lens,  therefore,  of  two  inches  focal  length, 
magnifies  five  diameters  ;  of  one  inch  focus,  ten  diameters  ; 
of  one-half  inch,  twenty  diameters  ;  of  one-eighth  inch, 
eighty  diameters  ;  etc. 

Simple  microscopes  are  now  seldom  used,  except  as 
hand  magnifiers,  or  for  the  minute  dissection  and  prepa- 
ration of  objects.  They  are  used  for  the  latter  purpose, 
when  suitably  mounted  with  a  convenient  arm,  mirror, 
etc.,  because  of  the  inconvenience  of  larger  and  otherwise 
more  perfect  instruments. 

Single  lenses,  of  large  size,  are  also  used  for  concentra- 
ting the  light  of  a  lamp  on  an  object  during  dissection,  or 
on  an  opaque  object  on  the  stage  of  a  compound  micro- 
scope. 

There  are  imperfections  of  vision  attending  the  use  of 
all  common  lenses,  arising  from  the  spherical  shape  of  the 
surface  of  the  lens,  or  from  the  separation  of  the  colored 
rays  of  light  when  passing  through  such  a  medium. 
These  imperfections  are  called  respectively  spherical  and 
chromatic  aberration.  To  lessen  or  destroy  these  aberra- 
tions, various  plans  have  been  proposed  by  opticians.  For 
reducing  spherical  aberration,  Sir  John  Herschel  pro- 
posed a  doublet  of  two  plano-convex  lenses,  whose  focal 
lengths  are  as  2.3  to  1,  with  their  convex  sides  together; 


THE    MICROSCOPE.  23 

and  Mr.  Coddington  invented  a  lens  in  the  form  of  a 
sphere,  cut  awray  round  the  centre  so  as  to  assume  the 
shape  of  an  hour-glass.  This  latter,  in  a  convenient  set- 
ting, is  one  of  the  best  pocket  microscopes.  Dr.  Wollas- 
ton's  doublet  consists  of  two  plano-convex  lenses,  whose 
focal  lengths  are  as  1  to  3,  with  the  plane  sides  of  each 
and  the  smallest  lens  next  the  object.  They  should  be 

FIG.  1. 


Holland's  Triplet. 

about  the  difference  of  their  focal  lengths  apart,  and  a 
diaphragm  or  stop — an  opaque  screen  with  a  hole  in  it — 
placed  just  behind  the  anterior  lens.  This  performs  ad- 
mirably, yet  has  been  further  improved  by  Mr.  Holland 
by  making  a  triplet  of  plano-convex  lenses  (Fig.  1),  with 
the  stop  between  the  upper  lenses. 

The  Compound  Microscope  consists  essentially  of  two 
convex  lenses,  placed  some  distance  apart,  so  that  the 
image  made  by  one  may  be  magnified  by  the  other. 
These  are  called  the  object-glass  and  the  eye-glass.  In 
Fig.  2,  A  is  the  object-glass,  which  forms  a  magnified 
image  at  c,  which  is  further  enlarged  by  the  eye-glass  B. 
An  additional  lens,  D,  is  usually  added,  to  enlarge  the 
field  of  view.  This  is  called  the  field-glass.  Its  office,  as 
in  the  figure,  is  to  collect  more  of  the  rays  from  the 
object-glass  and  form  an  image  at  F,  which  is  viewed  by 
the  eye-glass. 

Owing  to  chromatic  aberration,  an  instrument  of  this 
kind  is  still  imperfect,  presenting  rings  of  color  round  the 
edge  of  the  field  of  view  as  well  as  at  the  edge  of  the 
magnified  image  of  an  object,  together  with  dimness  and 


2-4 


THE    MICROSCOPIST. 


confusion  of  vision.  This  may  be  partly  remedied  by  a 
small  hole  or  stop  behind  the  object-glass,  which  reduces 
the  aperture  to  the  central  rays  alone,  yet  it  is  still  un- 


FIG.  2. 


Compound  Microscope. 


satisfactory.     Some  considerable  improvement  may  result 
from  using  Wollaston's  doublet  as  an  object-glass,  but  the 


THE    MICROSCOPE. 


25 


achromatic  object-glasses  now  supplied  by  good  opticians 
leave  nothing  to  be  desired. 

Object-glasses. — A  general  view  of  an  achromatic  object- 
glass  is  given  in  Fig.  3.  It  is  a  system  of  three  pairs  of 
lenses,  1,  2,  3,  each  composed  of  a  double  convex  of  crown 
glass  and  a  plano-concave  of  flint,  a,  6,  c,  represents  the 
angle  of  aperture,  or  the  cone  of  rays  admitted.  It  is 
unnecessary  to  consider  the  optical  principles  which  un- 
derlie this  construction.  Different  opticians  have  different 
formulae  and  propose  various  arrangements  of  lenses,  and 
there  is  room  for  choice  among  the  multitude  of  micro- 
scopes presented  for  sale.  For  high  powers,  the  German 


FIG.  3. 


FIG.  4. 


pss^^^^^l 


Achromatic  Object-glass. 


Huygenian  Eye-piece. 


and  French  opticians  have  lately  proposed  a  principle  of 
construction  which  is  known  as  the  immersion  system. 
It  consists  in  the  interposition  of  a  drop  of  water  between 
the  front  lens  of  the  objective  and  the  covering  glass  over 
the  object.  This  form  of  object-glass  is  corning  into  gen- 
eral use.  For  the  more  perfect  performance  of  an  objec- 
tive, it  is  necessary  that  it  should  be  arranged  for  correct- 
ing the  effect  of  different  thicknesses  of  covering  glass. 
This  is  accomplished  by  a  fine  screw  movement,  which 
brings  the  front  pair  of  lenses  (1,  Fig.  3)  nearer  or  further 
from  the  object.  In  this  way  the  most  distinct  and  accu- 
rate view  of  an  object  may  be  obtained. 


26  THE    MICROSCOPIST. 

Eye  pieces. — The  eye-piece  usually  employed  is  the  Huy- 
genian,  or  negative  eye-piece  (Fig.  4).  This  is  composed 
of  two  plano-convex  lenses,  with  their  plane  sides  next 
the  eye.  Their  focal  lengths  are  as  1  to  3,  and  their 
distance  apart  half  the  sum  of  their  focal  distances. 
Several  of  these,  having  different  magnifying  powers,  are 
supplied  with  good  microscopes.  It  is  best  to  use  a  weak 
eye-piece,  increasing  the  power  of  the  instrument  by 
stronger  objectives  when  necessary.  Kellner's  eye-piece 
has  the  lens  next  the  eye  made  achromatic.  The  peri- 
scopic  eye-piece  of  some  of  the  German  opticians  has  both 
lenses  double  convex.  This  gives  a  larger  field  of  view 
with  some  loss  of  accurate  definition.  For  high  powers, 
I  have  used  a  strong  meniscus  in  place  of  the  lower  lens 
in  the  Huygehian  eye-piece.  Dr.  Eoyston  Pigott  has 
suggested  improvements  in  eye-pieces  by  using  an  inter- 
mediate Huygenian  combination,  reversed,  between  the 
objective  and  ordinary  eye-piece.  This  gains  power,  but 
somewhat  sacrifices  definition.  Still  better,  he  has  pro- 
posed an  aplanatic  combination,  consisting  of  a  pair  of 
slightly  overcorrected  achromatic  lenses,  mounted  mid- 
way between  a  low  eye-piece  and  the  objective.  This 
has  a  separating  adjustment  so  as  to  traverse  two  or 
three  inches.  The  focal  length  of  the  combination  varies 
from  one  and  a  half  to  three-fourths  of  an  inch.  The 
future  improvement  of  the  microscope  must  be  looked  for 
in  this  direction,  since  opticians  seem  to  have  approached 
the  limit  of  perfection  in  high  power  objectives,  some  of 
which  have  been  made  equivalent  to  g'oth  or  TJ0th  of  an 
inch  focal  length.  As  an  amplifier,  I  have  used  a  double 
concave  lens  of  an  inch  in  diameter  and  a  virtual  focus  of 
one  and  a  half  inches  between  the  object-glass  and  the 
eye:piece.  If  the  object-glass  be  a  good  one,  this  will 
permit  the  use  of  a  very  strong  eye-piece  with  little  loss 
of  defining  power,  and  greatly  increase  the  apparent  size 
of  the  object. 


THE    MICROSCOPE.  27 

Mechanical  Arrangements. — The  German  and  French 
opticians  devote  their  attention  chiefly  to  the  excellence 
of  their  glasses,  while  the  mechanical  part  of  their  instru- 
ments is  quite  simple,  not  to  say  clumsy.  They  seem  to 
proceed  on  the  principle  that  as  little  as  possible  should  be 
done  by  mechanism,  which  may  be  performed  by  the  hand. 
It  is  different  with  English  and  American  makers,  some 
of  whose  instruments  are  the  very  perfection  of  mechan- 
ical skill.  The  disparity  in  cost,  however,  for  instruments 
of  equal  optical  power  is  quite  considerable. 

Certain  mechanical  contrivances  are  essential  to  every 
good  instrument.  The  German  and  French  stands  are 
usually  vertical,  but  it  is  an  advantage  to  have  one  which 
can  be  inclined  in  any  position  from  vertical  to  horizontal. 
There  should  be  steady  and  accurate,  coarse  and  fine  ad- 
justments for  focussing  ;  a  large  and  firm  stage  with  ledge, 
etc.,  and  with  traversing  motions,  so  as  to  follow  an  object 
quickly,  or  readily  bring  it  into  the  field  of  view  ;  also  a 
concave  and  plane  mirror  with  universal  joints,  capable 
of  being  brought  nearer  or  farther  from  the  stage,  or  of 
being  turned  aside  for  oblique  illumination.  Steadiness, 
or  freedom  from  vibration,  is  of  the  utmost  importance  in 
the  construction,  since  every  unequal  vibration  will  be 
magnified  by  the  optical  power  of  the  instrument. 

Among  so  many  excellent  opticians  it  would  be  impos- 
sible to  give  a  complete  list  of  names  whose  workmanship 
is  wholly  reliable,  yet  among  the  foremost  may  be  men- 
tioned Tolles,  of  Boston ;  Wales,  of  Fort  Lee,  N.J.',  Gru- 
now,  of  New  York  ;  and  Zentmayer,  of  Philadelphia  ; 
Powell  &  Leland,  Ross  and  Smith,  Beck  &  Beck,  of  London  ; 
Hartnack  and  Cachet,  of  Paris ;  Merz,  of  Munich  ;  and 
Gundlach,  of  Berlin.  The  optical  performance  of  lenses 
from  these  establishments  is  first  class,  and  the  mechanical 
work  of  their  various  models  good.  The  finest  instru- 
ments from  these  makers,  with  complete  appliances,  are 
quite  costly,  except  the  Germans  and  French,  whose  ar- 


23  THE    MICROSCOPIST. 

rangements,  as  we  have  said,  are  more  simple.  Cheaper 
instruments,  however,  are  made  by  English  and  American 
opticians,  some  of  which  are  very  fine. 

Opticians  divide  microscopes  into  various  classes,  ac- 
cording to  the  perfection  of  their  workmanship  or  the 
accessories  supplied.  The  best  first-class  instruments  have 

Fio.  5.    f 


Wenham's  Prism  for  the  Binocular  Microscope. 

a  great  variety  of  objectives  and  eye-glasses,  mechanical 
stage  with  rack- work ;  a  sub-stage  with  rack  for  carrying 
various  illuminators  :  a  stand  of  most  solid  construction  ; 
and  every  variety  of  apparatus  to  suit  the  want  or  wish 
of  the  observer.  They  are  great  luxuries,  although  not 
essential  to  perfect  microscopic  work.  The  second  class, 
or  students'  microscopes,  have  less  expensive  stands,  but 
equal  optical  powers,  with  first-class  instruments.  The 


FIG.  6. 


Collins's  Harley  Binocular  Microscope. 


30  THE    MICROSCOPIST. 

third  or  fourth  classes  of  instruments  are  intended  for 
popular  and  educational  use,  and  are  fitted  not  only  with 
stands  of  more  simple  workmanship,  but  with  cheaper 
lenses,  although  often  very  good.  Some  French  achro- 
matic objectives,  adapted  to  this  class,  are  suitable  for  all 
but  the  very  finest  work. 

Binocular  Microscopes. — The  principle  of  the  stereoscope 
has  been  applied  to  the  microscope,  so  as  to  permit  the 
use  of  both  eyes.  The  use  of  such  an  instrument  with 
low  or  medium  powers  is  very  satisfactory,  but  is  less 
available  with  objectives  stronger  than  one-half  inch  focus. 
There  are  two  ways  of  accomplishing  a  stereoscopic  effect 
in  the  microscope.  The  first  and  most  common  is  by 
means  of  Wenham's  prism  (Fig.  5),  placed  above  the  ob- 
jective, and  made  to  slide  so  as  to  transform  the  binocular 
into  a  monocular  microscope. 

The  second  mode  is  to  place  an  arrangement  of  prisms 
in  the  eye-piece,  so  as  to  refract  one-half  the  image  to  the 
right  and  the  other  half  to  the  left,  which  are  viewed  by 
the  corresponding  eyes.  In  either  construction  there  is  a 
provision  made  for  the  variable  distance  between  the  eyes 
of  different  observers.  In  the  frontispiece  is  a  representa- 
tion of  Zentmayer's  grand  American  microscope,  which 
will  afford  a  good  idea  of  the  external  appearance  of  a 
first-class  binocular  microscope.  Students'  and  third-class 
microscopes,  as  before  said,  are  less  complicated  and  of 
more  moderate  cost.  The  mechanical  and  optical  per- 
formance of  Zentmayer's  large  instrument  leaves  scarcely 
anything  to  be  desired.  Instead  of  the  more  expensive 
rack-work  stage,  a  simple  form,  originally  invented  by  Dr. 
Keen,  of  Philadelphia,  and  copied  by  Nachet  and  others, 
is  often  employed.  It  consists  of  a  rotating  glass  disk,  to 
which  is  attached  a  spring,  or  a  V-shaped  pair  of  springs, 
armed  with  ivory  knobs,  which  press  upon  a  glass  plate 
in  the  object-carrier.  The  motion  is  exceedingly  smooth 
and  effective. 


FIG.  7. 


Beck  s  Large  Compound  Microscope. 
FIG.  8.  FIG.  9. 


Hartnack's  Small  Model  Microscope. 


Nachet's  Inverted  Microscope. 


32  THE    MICROSCOPIST. 

Fig.  6  shows  Collins's  Harley  binocular  microscope,  a 
good  second  class  instrument. 

Fig.  7  represents  Beck's  large  compound  miscroscope 
(monocular) ;  and  Fig.  8,  Hartnack's  small  model  micro- 
scope, with  the  body  made  to  incline. 

Fig.  9,  Cachet's  inverted  microscope,  invented  by  Dr. 
Lawrence  Smith  for  chemical  investigations. 


CHAPTER    III. 

MICROSCOPIC   ACCESSORIES. 

IN  addition  to  the  object-glasses,  eye-glasses,  mirror, 
and  mechanical  arrangement  of  the  microscope,  to  which 
reference  was  made  in  the  last  chapter,  several  accessory 
instruments  will  be  useful  and  even  necessary  for  certain 
investigations. 

The.  Diaphragm,  for  cutting  off  extraneous  light  when 
viewing  transparent  objects,  is  generally  needed.  In  some 
German  instruments  it  consists  of  a  cylinder  or  tube,  whose 
upper  end  is  fitted  with  a  series  of  disks  having  central 
openings  of  different  sizes.  The  disk  can  be  adjusted  to 
variable  distances  from  the  object  on  the  stage  so  as  to 
vary  its  effects.  English  and  American  opticians  prefer 
the  rotary  diaphragm,  which  is  of  circular  form,  perforated 
with  holes  of  different  sizes,  and  made  to  revolve  under 
the  stage.  The  gradual  reduction  of  light  can  be  accom- 
plished by  the  cylinder  diaphragm,  since  when  it  is  pushed 
up  so  as  to  be  near  the  stage  it  cuts  off  only  a  small  part 
of  the  cone  of  rays  sent  upwards  by  the  concave  mirror, 
but,  when  drawn  downwards,  it  cuts  off  more. 

Collins's  Graduating  Diaphragm,  which  is  made  with 
four  shutters,  moving  simultaneously  by  acting  on  a  lever 


MICROSCOPIC    ACCESSORIES.  §3 

handle,  so  as  to  narrow  the  aperture,  accomplishes  the 
end  most  perfectly.     (Fig  10.) 


FIG.  10. 


Collins's  Now  (jrr  dilating  Diaphragm. 


Beck's  Iris  Diaphragm,  is  a  further  improvement  of  this 
sort. 

Condensers. — The  loss  of  light  resulting  from  the  em- 
ployment of  high  powers  has  led  to  several  plans  for  con- 
densing light  upon  the  object.  Sometimes  a  plano-convex 
lens,  or  combination  of  lenses,  is  made  to  slide  up  and 
down  under  the  stage.  A  Kellner's  eyepiece,  or  some 

FIG.  11. 


Smith  and  Beck's  Achromatic  Condenser. 


similar  arrangement,  especially  if  fitted  with  a  special 
diaphragm,  containing  slits  and  holes,  some  of  the  latter 
having  central  stops,  is  of  very  great  use.  First-class  in- 
struments are  fitted  up  with  achromatic  condensers  (Fig. 
11),  carrying  revolving  diaphragms,  some  of  whose  aper- 


34  THE    MICROSCOPIST. 

tures  are  more  or  less  occupied  by  stops,  or  solid  disks,  so 
as  to  leave  but  a  ring  of  space  for  light  to  pass  through. 
The  effect  of  these  annular  diaphragms  is  similar  to  an 
apparatus  for  oblique  illumination. 

The  Webster  condenser  is  similar  in  its  optical  parts  to 
the  Kellner  eye-piece,  and  is  provided  with  a  diaphragm 
plate,  with  stops  for  oblique  illumination,  as  well  as  a 


FIG.  12. 


Webster's  Condenser,  with  Graduating  Diaphragms. 

graduating  diaphragm  for  the  regulation  of  the  central 
aperture.     This  is  a  most  useful  accessory.     (Fig.  12.) 

Oblique  Illuminators  — Certain  fine  markings  on  trans- 
parent objects  can  scarcely  be  made  out  by  central  illumi- 
nation, but  require  the  rays  to  come  from  one  side,  so  as 
to  throw  a  shadow.  Sometimes  this  is  well  accomplished 
by  turning  the  mirror  aside  from  the  axis  of  the  micro- 
scope, and  sometimes  by  the  use  of  one  of  the  condensers 
referred  to  above.  AmicCs  prism,  which  has  both  plane 
and  lenticular  surfaces,  is  sometimes  used  on  one  side  and 
under  the  stage,  in  lieu  of  the  mirror.  For  obtaining 
very  oblique  pencils  of  light  the  double  hemispherical  con- 
denser of  Mr.  Reade  has  been  invented.  It  is  a  hemi- 
spherical lens  of  about  one  and  a  half  inch  diameter,  with 
its  flat  side  next  the  object,  surmounted  by  a  smaller  lens 
of  the  same  form,  the  flat  side  of  which  is  covered  with  a 
thin  diaphragm,  having  an  aperture  or  apertures  close  to 


MICROSCOPIC    ACCESSORIES. 


35 


its  margin.  These  apertures  may  be  Y-shaped,  extending 
to  about  a  quarter  of  an  inch  from  the  centre. 

If  the  microscope  has  a  mechanical  stage,  with  rack- 
work,  or  is  otherwise  too  thick  to  permit  the  mirror  to 
be  turned  aside  for  very  oblique  illumination,  Nachefs 
prism  will  prove  of  service.  I  have  also  contrived  a  useful 
oblique  illuminator  for  this  purpose,  by  cementing  with 
Dammar  varnish  a  plano-convex  lens  on  one  face  of  a  to- 
tally-reflecting  prism,  and  near  the  upper  edge  of  the 
other  side  (at  90°)  an  achromatic  lens  from  a  French  trip- 
let. The  prism  is  made  to  turn  on  a  hinge,  so  that  an 
accurate  pencil  of  light  may  fall  on  the  object  at  any 
angle  desired. 

Dark-ground  Illuminators. — Some  beautiful  effects  are 
produced,  and  the  demonstration  of  some  structures  aided, 
by  preventing  the  light  condensed  upon  the  object  from 
entering  the  object-glass.  In  this  way  the  object  appears 


FIG.  13. 


FIG.  14. 


Nobert's  Illuminator. 


Parabolic  Illuminator. 


self-luminous  on  a  black  ground.  For  low  powers  this 
can  be  easily  done  by  turning  aside  the  concave  mirror  as 
in  oblique  illumination,  or  by  employing  Nobert's  illumi- 
nator, which  is  a  thick  plano-convex  lens,  in  the  convex 


36 


THE    MICROSCOPIST. 


surface  of  which  a  deep  concavity  is  made.  The  plane 
side  is  next  the  object.  This  throws  an  oblique  light  all 
round  the  object.  A  substitute  for  this,  called  a  spot  lens, 
is  often  used,  and  differs  only  from  Robert's  in  having  a 
central  black  stop  on  the  plane  side  instead  of  a  concavity 
(Fig.  13).  A  still  greater  degree  of  obliquity  suitable  for 
high  powers  must  be  sought  by  the  use  of  the  parabolic 
illuminator  (Fig.  14).  This  is  usually  a  paraboloid  of  glass, 
which  reflects  to  a  focus  the  rays  which  fall  upon  its  inter- 
nal surface,  while  the  central  rays  are  stopped. 

Illuminators  for  Opaque  Objects. — Ordinary  daylight  is 
hardly  sufficient  for  the  illumination  of  opaque  objects, 

FIG.  15. 


Bull's-eye  Condenser. 


so  that  microscopists  resort  to  concentrated  lamplight,  etc. 
Gas,  paraffine,  and  camphene  lamps,  have  been  variously 
modified  for  this  purpose,  but  few  are  better  than  the  Ger- 


MICROSCOPIC  ACCESSORIES.  37 

man  student's  Argand  lamp  for  petroleum  or  kerosene 
oil,  as  it  is  called.  To  concentrate  the  light  from  such  a 
source  a  condensing  lens  is  used,  either  attached  to  the 
microscope  or  mounted  on  a  separate  stand.  Sometimes 
a  bull's-eye  condenser  is  used  for  more  effective  illumination 
(Fig.  15).  This  is  a  large  plano-convex  lens  of  short  focus, 
mounted  on  a  stand.  For  such  a  lens  the  position  of  least 
spherical  aberration  is  when  its  convex  side  is  towards 
parallel  rays ;  hence,  in  daylight,  the  plane  side  should  be 
next  the  object.  But,  if  it  is  desired  to  render  the  diverg- 


FIG.  16. 


Parabolic  Speculum. 

ing  rays  of  a  lamp  parallel,  the  plane  side  should  be  next 
the  lamp,  and  rather  close  to  it.  The  use  of  this  con- 
denser will  also  commend  itself,  when  used  as  last  referred 
to,  in  microscopic  dissection.  It  will  throw  a  bright  light 
from  the  lamp  directly  on  the  trough,  watch-glass,  etc.,  in 
which  the  specimen  is  being  prepared.  The  Lieberkuhn, 
or  a  concave  speculum  attached  to  the  object-glass,  and 
reflecting  the  light  from  the  mirror  directly  upon  the 
object,  is  one  of  the  oldest  contrivances  for  the  illumina- 
tion of  opaque  objects ;  but  the  most  convenient  instru- 
ment is  the  parabolic  speculum  (Fig.  16),  a  side  mirror  with 


38  THE    MICROSCOPIST. 

a  parabolic  surface  attached  to  the  objective.  For  high 
powers,  a  lateral  aperture  above  the  objective  has  been 
made  to  throw  the  light  down  through  the  object-glass 
itself  by  means  of  a  small  reflector,  as  devised  by  Prof. 
Smith,  or  a  disk  of  thin  glass,  as  in  Beck's  vertical  illumi- 
nator. This  latter  is  attached  to  an  adapter  interposed 
between  the  objective  and  the  body  of  the  microscope. 

Instruments  for  Measuring  and  Drawing  Objects. — Screw 
micrometers  are  sometimes  used  with  the  microscope,  as 
with  the  telescope,  for  the  measurement  of  objects ;  but 
the  less  expensive  and  simpler  glass  micrometers  have 
generally  superseded  them.  The  latter  are  of  two  sorts, 
the  stage  and  the  ocular  micrometer.  The  stage  micrometer 
is  simply  a  glass  slide,  containing  fine  subdivisions  of  the 
inch,  line,  etc.,  engraved  by  means  of  a  diamond  point. 
Jn  case  the  rulings  are  TJDths  and  j-^^fhs  of  an  inch,  it 
is  evident  that  an  object  may  be  measured  by  comparison 
with  the  divisions  ;  yet,  in  practice,  it  is  found  incon- 
venient to  use  an  object  with  the  stage  micrometer  in  this 
way,  and  it  will  be  found  better  to  combine  its  use  with 
that  of  the  drawing  apparatus,  as  hereafter  described. 
The  ocular,  or  eye-piece  micrometer,  is  a  ruled  slip  of  glass 
in  the  eye-piece.  Its  value  is  a  relative  one,  depending  on 
the  power  of  the  objective  and  the  length  of  the  micro- 
scope tube.  By  comparing  the  divisions  with  those  of  the 
stage  micrometer  their  value  can  be  readily  ascertained. 
Thus,  if  five  spaces  of  the  eye-piece  micrometer  cover  one 
space  of  the  stage  micrometer,  measuring  fo'oo^h  of  an 
inch,  their  value  will  be  2j0th  of  an  inch  each. 

Different  standards  of  measurement  are  used  in  different 
countries.  English  and  American  microscopists  use  the 
inch.  In  France,  and  generally  in  Germany,  the  Paris 
line  or  the  millimetre  is  used.  The  millimetre  is  0.4433  of 
a  Paris  line  and  0.4724  of  an  English  line  ( ,-^th  of  an 
inch). 

In  the  French  system  the  fundamental  unit  is  the  metre, 


MICROSCOPIC    ACCESSORIES. 


39 


which  is  the  ten-millionth  part  of  the  quadrant  of  the 
meridian  of  Paris.  The  multiples  are  made  by  prefixing 
Greek  names  of  numbers,  and  the  subdivisions  by  prefix- 
ing Latin  names.  Thus,  for  decimal  multiples,  we  have 
deeo,  hecto,  kilo,  and  myrio  ;  and,  for  decimal  subdivisions, 
deci,  centi,  and  milli.  The  following  may  serve  for  con- 
verting subdivisions  of  the  metre  into  English  equiva- 
lents : 

A  millimetre  equals  0.03937  English  inches. 

A  centimetre      "       0.39371  " 

A  decimetre        "       3.93708  " 

One  inch  =2.539954  centimetres,  or  25.39954  millimetres. 

For  drawing  microscopic  objects  the  camera  lucida  will 
be  found  useful.  This  is  a  small  glass  prism  attached  to 
the  eye-piece.  iThe  microscope  is  inclined  horizontally, 


FIG.  17. 


Oberhauser's  Drawing  Apparatus. 

and  the  observer,  looking  into  the  prism,  sees  the  object 
directly  under  his  eye,  so  that  its  outlines  may  be  drawn 
on  a  piece  of  paper  placed  on  the  table.  Some  practice, 
however,  is  needed  for  satisfactory  results.  For  the  up- 
right stands  of  German  and  French  microscopes,  the  camera 
lucida  of  Chevalier  &  Oberhauser  is  available.  This  is  a 
prism  in  a  rectangular  tube,  in  front  of  which  is  the  eye- 
piece, carrying  a  small  glass  prism  (c,  Fig.  17),  surrounded 


40  THE    MICROSCOPIST. 

by  a  black  metal  ring.  A  paper  placed  beneath  is  visible 
through  the  opening  in  the  ring,  and  the  image  reflected 
by  the  prism  upon  it  can  be  traced  by  a  pencil.  It  is  neces- 
sary to  regulate  the  light  so  that  the  point  of  the  pencil 
may  be  seen. 

Dr.  Beale  has  recommended,  in  lieu  of  the  camera  lucida, 
a  piece  of  slightly  tinted  plate  glass  (Fig.  18),  placed  in  a 
short  tube  over  the  eye-piece  at  an  angle  of  45°.  This  is 
a  cheap  and  effective  plan.  A  similar  purpose  is  served 

Flo.  18.  Fin.  19. 


Beale's  Tint-glass  Camera.  Scemmering's  Steel  Disk. 

by  a  little  steel  disk,  smaller  than  the  pupil  of  the  eye, 
placed  at  the  same  angle  (Fig.  19). 

The  most  simple  method  of  measuring  objects  is  to 
employ  one  of  the  above  drawing  instruments,  placing 
first  on  the  microscope  stage  an  ordinary  micrometer,  and 
tracing  its  lines  on  the  paper.  Then  the  outline  of  the 
object  can  be  traced  and  compared  with  the  lines.  The 
magnifying  power  of  an  object-glass  can  also  be  readily 
found  by  throwing  the  image  of  the  lines  in  a  stage 
micrometer  upon  a  rule  held  ten  inches  below  the  eye- 
piece, looking  at  the  magnified  image  with  one  eye  and 
at  the  rule  with  the  other.  Dr  Beale  strongly  urges 
observers  to  delineate  their  own  work  on  wood  or  stone, 
since  they  can  do  it  more  exactly  and  truthfully  than  the 


MICROSCOPIC    ACCESSORIES.  41 

most  skilled  artists  who  are  unfamiliar  with  microscopic 
manipulation. 

Other  accessory  apparatus,  such  as  a  frog-plate,  for  more 
readily  observing  the  circulation  in  a  frog's  foot ;  an 
animalcule  cage,  or  live  box ;  a  compressorium,  for  apply- 
ing pressure  to  an  object ;  fishing  tubes ;  watch-glasses  ; 
growing-slides,  etc.,  will  commend  themselves  on  personal 
inspection. 

For  preventing  the  evaporation  of  fluids  during  obser- 
vation, Recklinghausen  invented  the  moist  chamber  (Fig. 
20),  consisting  of  a  glass  ring  on  a  slide,  to  which  is  fas- 
tened a  tube  of  thin  rubber,  the  upper  end  of  which  is 
fastened  round  the  microscope  tube  with  a  rubber  band. 


Recklinghauseii's  Moist  (  liumbcr. 

A  simpler  form  of  moist  chamber  may  be  made  by  a 
glass  ring  cemented  on  a  slide.  A  few  drops  of  water 
cautiously  put  on  the  inner  edge  of  the  ring  with  a  brush, 
or  a  little  moist  blotting-paper  may  be  placed  inside.  The 
object  (as  a  drop  of  frog's  blood,  etc.)  may  then  be  put  on 
a  circular  thin  cover,  which  is  placed  inverted  on  the  ring. 
A  small  drop  of  oil  round  the  edge  of  the  cover  keeps  it 
air  and  water-tight. 

Somewhat  similar  to  the  above  is  Strieker's  gas  chamber 
(Fig.  21).  On  the  object-slide  is  a  ring  of  glass,  or  putty, 
with  its  thin  cover.  Through  this  ring  two  glass  tubes 
are  cemented,  one  of  which  is  connected  with  a  rubber 


42 


THE    MICROSCOPIST. 


tube  for  the  entrance  of  gas,  while  the  other  serves  for 
its  exit. 

For  the  study  of  phenomena  in  the  fluids,  etc.,  of  warm- 
blooded animals,  we  need,  in  addition  to  the  moist  cham- 
ber, some  way  of  keeping  the  object  warm.  This  may  be 
roughly  done  by  a  perforated  tin  or  brass  plate  on  the 
stage,  one  end  of  which  is  wrarmed  by  a  spirit-lamp.  A 
piece  of  cocoa  butter  or  wax  will  show  by  its  melting 
when  the  heat  is  sufficient.  Schultze's  warm  stage  is  a 
more  satisfactory  and  scientific  instrument.  It  is  a  brass 
plate  to  fit  on  the*  stage,  perforated  for  illumination,  and 
connected  with  a  spirit-lamp  and  thermometer,  so  that 


Fro.  21. 


Strieker's  Gas  Chamber. 


the  amount  of  heat  may  be  exactly  regulated.  Other 
arrangements  have  been  proposed  to  admit  a  current  of 
warm  water,  or  for  the  passage  of  electricity  through  an 
object  while  under  observation,  which  are  scarcely  neces- 
sary to  describe. 

The  Polariscope. — The  nature  and  properties  of  polarized 
light  belong  rather  to  a  treatise  on  optics  or  natural  phi- 
losophy than  to  a  work  like  the  present,  yet  a  very  brief 
account  may  not  be  out  of  place.  We  premise,  then,  that 
every  ray  or  beam  of  common  light  is  supposed  to  have 
at  least  two  sets  of  vibrations,  vertical  and  horizontal. 
As  these  vibrations  have  different  properties,  the  ray  when 


MICROSCOPIC    ACCESSORIES. 


43 


divided  is  said  to  be  polarized,  from  a  fancied  resemblance 
to  the  poles  of  a  magnet.  The  division  of  the  vibrations 
may  be  effected  (i. «?.,  the  light  may  be  polarized)  in  vari- 
ous ways.  For  the  microscope  the  polarizer  is  a  Nicholas 
prism,  composed  of  a  crystal  of  Iceland  spar,  which  has 
been  divided  and  again  cemented  with  Canada  balsam,  so 
as  to  throw  one  of  the  doubly  refracted  rays  aside  from 
the  field  of  view  (Fig.  22).  Such  a  prism  is  mounted  in 
a  short  tube  and  attached  to  the  under  side  of  the  stage. 
In  order  to  distinguish  the  effects  of  polarized  light,  an 
analyzer  is  also  needed.  This  usually  consists  of  another 


FIG.  22. 


FIG.  23. 


Nichol's  Pi  ism. 


Polarizer  and  Analyzer. 


similar  Nichol's  prism,  attached  either  to  the  eye-piece  or 
just  above  the  objective.  The  latter  position  gives  a 
larger  field,  but  the  former  better  definition.  Fig.  23 
shows  the  polarizer  and  the  analyzer.  The  polarizer  is 
improved  by  the  addition  of  a  convex  lens  next  the  object. 
Hartnack  has  also  improved  the  eye-piece  analyzer  by 
adding  a  graduated  disk  and  vernier. 

When  the  polarizer  arid  analyzer  have  been  put  in  place, 
they  should  be  rotated  until  their  polarizing  planes  are 
parallel,  and  the  mirror  adjusted  so  as  to  give  the  most 
intense  light.  If  now  the  polarizing  planes  are  placed  at 
right  angles,  by  turning  one  of  them  90°,  the  field  is  ren- 


44 


THE    MICROSCOPIST. 


dered  dark,  and  doubly  refracting  bodies  on  the  stage  of 
the  microscope  appear  either  illuminated  or  in  colors.  If 
a  polarized  ray  passes  through  a  doubly  refracting  film, 
as  of  selenite,  it  forms  two  distinct  rays,  the  ordinary 
and  the  extraordinary  ray.  Each  of  these  will  be  of  dif- 
ferent colors,  according  to  the  thickness  of  the  film.  Lf 
one  be  red,  the  other  will  be  green,  these  colors  being 
complementary.  By  using  the  analyzer  one  of  these  rays 
is  alternately  suppressed,  so  that  on  revolving  the  appa- 
ratus the  green  and  red  rays  appear  to  alternate  at  each 
quarter  of  a  circle.  Films  of  selenite  are  often  mounted 
so  as  to  revolve  between  the  polarizer  and  the  stage. 
Barker's  selenite  stage  is  sometimes  used  for  this  purpose 
(Fig.  24).  With  such  a  stage  a  set  of  selenites  is  usually 


i'!.  24. 


Barker's  Selenite  Stage. 

supplied,  giving  the  blue,  purple,  and  red,  with  their  com- 
plementary colors,  orange,  yellow,  and  green.  By  this 
combination  all  the  colors  of  the  spectrum  may  be  ob- 
tained. The  selenite  disks  generally  have  engraved  on 
them  the  amount  of  retardation  of  the  undulations  of 
white  light,  thus:  J,  f,  and  ».  If  these  are  placed  so 
that  their  positive  axes  (marked  PA)  coincide,  they  give 
the  sum  of  their  combined  retardations. 

The  Microspectroscope.  ^Ordinary  spectrum  analysis,  by 
determining  the  number  and  position  of  certain  narrow 
lines  in  the  spectra  of  luminous  bodies,  called  Fraunhofer's 


MICROSCOPIC    ACCESSORIES. 


45 


enables  the  chemist  to  identify  different  substances. 
The  object  of  the  microspectroscope  is  different.  It  en- 
ables us  to  distinguish  substances  by  the  absence  of  cer- 
tain rays  in  the  spectrum,  or,  in  other  words,  to  judge  of 
substances  by  a  scientific  examination  of  their  color.  The 
color  of  a  body  seen  with  the  naked  eye  is  the  general 
impression  made  by  the  transmitted  light,  and  this  may 
be  the  same  although  the  compound  rays  may  differ 


The  Sorby-Browning  Microspectroscope. 

greatly,  so  that  colors  which  seem  absolutely  alike  may 
be  distinguished  by  their  spectra.  Many  solutions  are 
seen  to  absorb  different  colors  in  very  definite  parts  of  the 
spectrum,  forming  absorption  bands  or  lines,  varying  in 
width  and  intensity  according  to  the  strength  of  the  so- 
lution. The  instrument  usually  employed  consists  of  a 
direct-vision  spectrum  apparatus  attached  to  the  eye  piece 
of  the  microscope,  which  shows  the  principal  Fraunhofer 


46 


THE    MICROSCOPIST. 


lines  by  daylight,  or  a  spectrum  of  the  light  transmitted 
by  any  object  in  the  field  of  view.  A  reflecting  prism  is 
placed  under  one-half  of  the  slit  of  the  apparatus  so  as  to 
transmit  from  a  side  aperture  a  standard  spectrum  for 
comparison.  In  Fig.  *25,  A  is  a  brass  tube  carrying  the 
compound  direct-vision  system  of  five  prisms  and  an 
achromatic  lens.  This  tube  is  moved  by  the  milled  head 


FIG.  2G. 


Spectroscope  with  Micrometer. 

B,  so  as  to  bring  to  a  focus  the  different  parts  of  the 
spectrum.  This  is  important  when  the  bands  or  lines  to 
be  examined  are  delicate.  D  is  the  stage  on  which  objects 
for  comparison  are  placed.  The  light  passing  through 
them  from  the  mirror  i,  goes  through  a  side  opening  to  a 
reflecting  prism  which  covers  a  part  of  a  slit  in  the  bot- 
tom of  the  tube  A.  This  slit  is  opened  and  shut  by  means 
of  the  screws  c  and  H.  Fig.  26  shows  the  internal  ar- 


MICROSCOPIC  ACCESSORIES.  47 

rangement  of  the  prisms  and  lens,  together  with  a  microm- 
eter for  measuring  the  position  of  lines  or  absorption 
bands.  To  use  the  microspectroscope,  remove  the  tube 
A,  with  the  prisms,  and  insert  the  tube  G  in  the  place  of 
the  eye-piece  of  the  microscope.  With  the  lowest  power 
object-glass  which  is  suitable,  and  the  slit  opened  wide  by 
the  screw  H,  the  object  on  the  stage  of  the  microscope, 
illuminated  by  the  mirror  or  condenser,  is  brought  to  a 
focus,  the  tube  A  replaced  and  adjusted  for  focus  by  the 
screw  B,  while  the  slit  is  regulated  by  c  and  H  until  a  well- 
defined  spectrum  is  seen.  To  determine  the  position  of 
the  absorption  lines,  remove  the  upper  cover  of  the  tube 
A  and  replace  it  with  that  carrying  the  micrometer  repre- 
sented in  Fig.  26.  The  mirror  illuminates  a  transparent 
line  or  cross,  whose  image  is  refracted  by  a  lens  c,  mov- 
able by  a  screw  B,  and  reflected  at  an  angle  of  45°  from 
the  upper  surface  of  the  prisms,  so  as  to  be  seen  upon  the 
spectrum.  By  means  of  the  micrometer  screw  M,  this  is 
made  to  move  across  the  spectrum,  so  that  the  distance 
between  the  lines  may  be  determined.  In  order  to  com- 
part the  results  given  by  different  instruments,  the 
observer  should  measure  the  position  of  the  principal 
Fraunhofer  lines  in  bright  daylight,  and  mark  them  on 
a  cardboard  scale,  which  may  be  preserved  for  reference. 
By  comparing  the  micrometric  measurement  of  lines  in 
the  spectrum  of  any  substance  observed  by  artificial  light 
with  such  a  scale,  their  position  may  readily  be  seen. 

In  using  the  microspectroscope  some  objects  require  a 
diaphragm  of  small  size,  and  others,  especially  with  the 
1J  or  2-inch  objective,  a  cap  with  a  hole  j'gth  of  an  inch 
in  diameter  over  the  end  of  the  microscope,  to  prevent 
extraneous  light  from  passing  through  the  tube. 

Nose-piece. — For  the  purpose  of  facilitating  observations 
with  objectives  of  different  powers  a  revolving  nose-piece 
has  been  contrived,  carrying  two,  three,  or  four  objectives, 


48  THE    M1CROSCOPIST 

which  may  be  brought  quickly  into  the  axis  of  the  instru- 
ment. 

Object-finders. — It  is  sometimes  tedious  to  find  a  small 
object  on  a  slide,  particularly  with  high  powers,  and  a 
number  of  contrivances,  as  Maltwood's  finder,  have  been 
proposed  for  this  end.  A  very  simple  method,  however, 
may  serve.  Mark  on  the  stage  two  crosses,  one  like  the 
sign  of  addition  -f,  and  the  other  like  the  sign  of  multi- 
plication x  ,  and,  when  the  object  is  found,  mark  the  slide 
to  correspond  with  the  marks  below.  If  the  stage  be  a 
mechanical  one  it  will  be  necessary  to  arrange  it  in  the 
previous  position. 

Microscopic  Photography. — Many  European  experimen- 
ters have  succeeded  in  taking  microscopic  photographs, 
but  a  great  advance  in  this  direction  has  been  made  under 
the  direction  of  the  medical  department  of  the  United 
States  army  at  Washington.  Lieutenant-Colonel  Wood- 
ward has  succeeded  in  furnishing  permanent  records  of 
many  details  of  structure,  which  exhibit  the  very  perfec- 
tion of  art.  In  a  work  like  the  present  a  full  account  of 
the  apparatus  and  methods  employed  would  be  out  of  place. 
Dr.  Beale's  How  to  Work  with,  the  Microscope,  and  the  re- 
ports issued  from  the  Surgeon-General's  office  at  Wash- 
ington, will  give  the  details. 


CHAPTER    IV. 

USE   OF    THE   MICROSCOPE. 


Care  of  the  Instrument. — But  little  satisfaction  will  be 
secured  in  microscopic  work  for  any  length  of  time  with- 
out scrupulous  care  of  the  lenses,  etc.,  belonging  to  the 
instrument,  and  habits  of  this  kind  should  be  early  ac- 
quired. When  in  frequent  use  the  microscope  should  be 


USE    OF    THE    MICROSCOPE.  49 

seldom  packed  away  in  its  case,  as  a  certain  necessary 
stiffness  of  motion  in  its  various  parts  might  thereby  be 
lessened.  Yet  it  should  be  kept  free  from  dust  and  damp. 
A  bell-glass  cover,  or  glass  case,  or  a  cabinet  which  will 
admit  the  reception  of  the  instrument  in  a  form  ready  for 
immediate  use,  is  desirable.  Before  using,  the  condition 
of  objective  and  eye-piece  should  be  examined  as  well  as 
of  the  mirror,  and  dust  or  dampness  removed.  Another 
examination  should  be  made  before  the  microscope  is  put 
away. 

Stains  on  the  brass-work  may  be  removed  by  a  linen 
rag,  and  dust  on  the  mirror  and  lenses  by  a  fine  camel's- 
hair  brush,  or  very  soft  and  clean  chamois  skin.  Frequent 
wiping  will  injure  the  polish  of  the  lenses. 

The  upper  surfaces  of  the  lenses  in  the  eye-pieces  and 
the  mirror  will  need  the  most  frequent  attention  The 
objectives,  if  carefully  handled  and  kept  in  their  boxes 
when  not  in  use,  will  seldom  require  cleaning.  If  the  front 
of  the  objective  becomes  accidentally  wet  with  fluid  it 
should  be  at  once  removed,  and,  when  reagents  are  used, 
great  care  should  be  taken  to  prevent  contact  with  the 
front  of  the  lens. 

Care  of  the  Eyes. — Continuous  observation,  especially  by 
lamplight,  and  with  high  powers,  has  doubtless  a  ten- 
dency to  injure  the  sight.  To  cease  work  as  soon  as 
fatigue  begins  is,  however,  a  simple  but  certain  rule  for 
protection.  This  time  will  vary  greatly,  according  to  the 
general  tone  and  vigor  of  the  observer.  It  is  also  impor- 
tant to  use  the  eyes  alternately  if  a  monocular  instrument 
is  employed,  as  otherwise  great  difference  both  in  the 
focus  and  in  the  sensitiveness  of  the  eyes  will  result.  The 
habit  of  keeping  the  unemployed  eye  open  is  a  good  one, 
and,  though  troublesome  at  first,  is  not  difficult  to  ac- 
quire. It  is  well  to  protect  the  eye  from  all  extraneous 
light,  and  to  exclude  every  part  of  the  object  except  that 
which  is  under  immediate  observation.  The  diaphragm 

4 


50  THE    MICROSCOPIST. 

will  serve  this  end  as  well  as  modify  the  quality  of  the 
light.  For  very  del  it-ate  observations  a  dark  shade  over 
the  stage,  which  may  be  fastened  by  an  elastic  ring  to 
the  microscope-tube,  so  as  to  shut  off  extraneous  light, 
will  be  useful. 

Table,  etc. — The  microscopist's  work-table  should  be 
large  and  massive,  so  as  to  be  convenient  and  free  from 
vibration.  Drawers  for  accessories  and  materials  used  in 
preparing  and  mounting  objects  are  also  desirable,  as  well 
as  a  few  bell-glasses  for  secluding  objects  from  dust.  Re- 
agents should  always  be  removed  from  the  table  after  use 
and  kept  in  another  place. 

Light. — Dr.  Carpenter  has  well  said,  "  Good  daylight  is 
to  be  preferred  to  any  other  kind  of  light,  but  good  lamp- 
light is  preferable  to  bad  daylight."  A  clear  blue  ftky 
gives  light  enough  for  low  powers,  but  a  dull  white 
cloudiness  is  better.  The  direct  rays  of  the  sun  are  too 
strong,  and  should  be  modified  by  a  white  curtain,  reflec- 
tion from  a  surface  of  plaster  of  Paris,  or,  still  better,  by- 
passing through  a  glass  cell  containing  a  solution  of  am- 
monio-sulphate  of  copper. 

Various  kinds  of  lamps  have  been  contrived  for  micro- 
scopic use ;  among  the  best  are  the  German  and  French 
"  student's  reading  lamps,"  which  burn  coal  oil  or  petro- 
leum. It  is  o'ften  useful  to  moderate  such  a  light  by  the 
use  of  a  chimney  of  blue  glass,  or  by  a  screen  of  blue  glass 
between  the  flame  and  the  object.  Dr.  Curtis  contrived 
a  useful  apparatus,  consisting  of  a  short  petroleum  lamp 
placed  in  an  upright,  oblong  box.  On  one  side  of  the  box 
is  an  opening  occupied  with  blue  glass ;  on  another  side 
the  opening  has  ground-glass,  as  well  as  a  piece  colored 
blue,  and  a  plano-convex  lens  so  placed  as  to  condense  the 
light  thus  softened  to  a  suitable  place  on  the  table. 

As  a  general  rule  the  light  should  come  from  the  left 
side,  and  that  position  assumed  or  inclination  given  to  the 
instrument  which  is  most  comfortable  to  the  observer. 


USB    OF    THE    MICROSCOPE.  51 

English  and  American  microscopists  prefer  an  inclined 
microscope,  while  the  German  and  French  instruments 
being  usually  vertical  do  not  permit  this  arrangement. 

Adjustment. — The  details  of  microscopic  adjustments 
are  only  to  be  learned  by  practice,  yet  a  few  directions 
may  be  instructive.  The  selection  of  the  objectives  and 
eye-pieces  depends  on  the  character  of  the  object.  As  a 
general  rule,  the  lowest  powers  which  will  exhibit  an 
object  are  the  best.  It  is  best  to  use  weak  eye-pieces  with 
the  stronger  objectives,  yet  much  depends  on  the  perfec- 
tion of  the  glasses  employed. 

The  focal  adjustment  can  be  made  with  the  coarse  ad- 
justment or  quick  motion  when  low  powers  are  employed ; 
but  for  higher  powers  the  fine  adjustment  screw  is  essen- 
tial. Care  must  be  taken  not  to  bring  the  objective  into 
close  or  sudden  contact  with  the  thin  glass  cover  over  the 
object,  and,  in  changing  object-glasses,  the  microscope 
body  should  be  raised  from  the  stage  by  the  coarse  adjust- 
ment. 

The  actual  distance  between  the  object  and  object-glass 
is  much  less  than  the  nominal  focal  length,  so  that  the 
1  inch  objective  has  a  working  distance  of  about  J  an 
inch,  the  Jth  of  about  ^th  of  an  inch,  while  shorter  ob- 
jectives require  the  object  to  be  covered  with  the  thinnest 
glass. 

Sometimes,  in  'high  powers,  and  especially  with  immer- 
sion-lenses, an  adjustment  of  the  object-glass  is  necessary 
in  order  to  suit  the  thickness  of  the  glass  cover.  With 
thick  covers  the  individual  lenses  must  be  brought  nearer 
to  each  other,  and,  with  very  thin  covers,  moved  farther 
apart. 

If  immersion-objectives  be  employed  a  drop  of  water  is 
placed  on  the  glass  cover  with  a  glass  rod  or  camel's-hair 
pencil,  and  a  second  drop  on  the  lens.  The  lens  and  object 
are  then  approximated  till  the  drops  flow  together  and  the 
focus  is  adjusted.  By  turning  the  Fcrew  of  the  objective 


52  THE    MICROSCOPIST. 

and  using  the  fine  adjustment  the  best  position  will  be 
shown  by  the  sharper  and  more  delicate  image  of  the 
object. 

For  other  details  respecting  adjustment  the  reader  is 
referred  to  the  chapter  on  Microscopic  Accessories. 

Errors  of  Interpretation. — True  science  is  hindered  most 
of  all  by  speculation  and  false  philosophy,  which  often 
assume  its  garb  and  name,  but  it  is  also  retarded  by  im- 
perfect or  false  observation.  It  is  much  less  easy  to  see 
than  beginners  imagine,  and  still  less  easy  to  know  what 
we  see.  The  latter  sometimes  requires  an  intellect  of  sur- 
passing endowments.  The  sources  of  error  are  numerous, 
but  some  require  special  caution,  and  to  these  we  now 
refer. 

The  nature  of  microscopic  images  causes  error  from 
imperfect  focal  adjustment.  We  see  distinctly  only  that 
stratum  of  an  object  which  lies  directly  in  focus,  and  it  is 
seldom  that  all  parts  of  an  object  can  be  in  focus  together. 
Hence  we  only  recognize  at  once  the  outline  of  an  object, 
but  not  its  thickness,  and,  as  the  parts  which  are  out  of 
focus  are  indistinct,  we  may  readily  fall  into  error.  Glasses 
vary  much  in  this  respect.  Some  have  considerable  pene- 
trating and  defining  power  even  with  moderate  angular 
aperture,  and  are  better  for  general  work  than  those  more 
perfect  instruments  which  give  paler  images  and  only  re- 
veal their  excellencies  to  the  practiced  microscopist. 

Sometimes  the  focal  adjustment  leads  to  error  on  ac- 
count of  the  reversal  of  the  lights  and  shadows  at  differ- 
ent distances.  Thus  the  centres  of  the  biconcave  blood- 
disks  appear  dark  when  in  focus,  and  bright  when  a  little 
within  the  focus ;  while  the  hexagonal  elevations  of  a  dia- 
tom, as  the  Pleurosigma  angulatum,&re  light  when  in  focus, 
with  dark  partitions,  and  dark  when  just  beyond  the 
focus.  From  this  we  gather  a  means  of  discrimination, 
since  a  convex  body  appears  lighter  by  raising  the  micro- 
scope, and  a  concave  by  lowering  it. 


USB    OF    THE    MICROSCOPE.  53 

The  refractive  power  of  the  object,  or  of  the  medium  in 
which  it  lies,  is  sometimes  a  source  of  error.  Thus  a 
human  hair  was  long  thought  to  be  tubular,  because  of 
the  convergence  of  the  rays  of  light  on  its  cylindrical  con- 
vexity. A  glass  cylinder  in  balsam  appears  like  a  flat 
band,  because  of  the  nearly  equal  refractive  powers  of 
object  and  medium.  The  lacunae  and  canaliculse  of  bone 
were  long  considered  solid,  because  of  the  dark  appear- 
ance presented  on  account  of  the  divergence  of  the  rays 
passing  through  them.  Their  penetration  with  Canada 
balsam,  however,  proves  them  to  be  cavities.  Air-bubbles, 
from  refraction,  present  dark  rings,  and,  if  present  in  a 
specimen,  seldom  fail  to  attract  the  first  attention  of  an 
inexperienced  observer.  The  difference  between  oil-globules 
in  water  and  water  in  oil,  or  air-bubbles,  should  be  early 
learned,  as  in  some  organized  structures  oil-particles  and 
vacuoles  (or  void  spaces)  are  often  interspersed.  A  globule 
of  oil  in  water  becomes  darker  as  the  object-glass^  is  de- 
pressed, and  lighter  when  raised  ;  while  the  reverse  is  the 
case  with  water  in  oil,  since  the  difference  of  refraction 
causes  the  oil  particles  to  act  as  convex  lenses,  and  those 
of  water  like  concave  lenses. 

Other  errors  arise  from  the  phenomena  of  motion  visible 
under  the  microscope.  A  dry  filament  of  cotton,  or  other 
fabric  absorbing  moisture,  will  often  oscillate  and  twist 
in  a  curious  way. 

If  alcohol  and  water  are  mixed^  the  particles  suspended 
acquire  a  rapid  motion  from  the  currents  set  up,  which 
continues  till  the  fluids  are  thoroughly  blended.  Nearly 
all  substances  in  a  state  of  minute  division  exhibit,  when 
suspended  in  fluid,  a  movement  called  the  "  Brownonian 
motion,"  from  Dr.  Robert  Brown,  who  first  investigated 
it.  It  is  a  peculiar,  uninterrupted,  dancing  movement,  the 
cause  of  which  is  still  unexplained.  These  movements, 
as  all  others,  appear  more  energetic  wThen  greatly  magni- 
fied by  strong  objectives.  It  requires  care  to  discriminate 


54  .        THE    MICROSCOPIST. 

between  such  motions  and  the  vital  or  voluntary  motions 
of  organized  bodies.  • 

The  inflection  or  diffraction  of  light  is  another  source 
of  error,  since  the  sharpness  of  outline  in  an  object  is  thus 
impaired.  The  shadow  of  an  opaque  object  in  a  divergent 
pencil  of  light  presents,  not  sharp,  well-defined  edges,  but 
a  gradual  shading  off,  from  which  it  is  inferred  that  the 
rays  do  not  pass  from  the  edge  of  the  object  in  the  same 
line  as  they  come  to  it.  This  is  in  consequence  of  the 
undulatory  nature  of  light.  When  any  system  of  wraves 
meets  with  an  obstacle,  subsidiary  systems  of  waves  will 
be  formed  round  the  edge  of  the  obstacle  and  be  propagated 
simultaneously  with  the  original  undulations.  For  a  cer- 
tain space  around  the  lines  in  which  the  rays,  grazing  the 
edge  of  the  opaque  body,,  would  have  proceeded,  the  two 
systems  of  undulation  will  intersect  and  produce  the  phe- 
nomena of  interference.  If  the  opaque  body  be  very  small, 
and  the  distance  from  the  luminous  point  proportionally 
large,  the  two  pencils  formed  by  inflection  will  intersect, 
and  all  the  phenomena  of  interference  will  become  evident. 
Thus,  if  the  light  be  homogeneous,  a  bright  line  of  light 
will  be  formed  under  the  centre  of  the  opaque  object,  out- 
side of  which  will  be  dark  lines,  and  then  bright  and  dark 
lines  alternately.  If  the  light  be  compound  solar  light,  a 
series  of  colored  fringes  will  be  formed.  In  addition  to 
the  results  of  inflection,  oblique  illumination  at  certain 
angles  produces  a  double  image,  or  a  kind  of  overlying 
shadow,  sometimes  called  the  "diffraction  spectrum," 
although  due  to  a  different  cause.  No  rules  can  be  given 
for  avoiding  errors  from  these  optical  appearances,  but 
practice  will  enable  one  to  overcome  them,  as  it  were, 
instinctively. 

Testing  the  Microscope. — The  defining  power  of  an  in- 
strument depends  on  the  correction  of  its  spherical  and 
chromatic  aberrations,  and  excellence  may  often  be  ob- 
tained with  objectives  having  but  a  moderate  angle  of 


USE    OF    THE    MICROSCOPE.  55 

aperture.  It  may  be  known  by  the  sharp  outline  given 
to  the  image  of  an  object,  which  is  not  much  impaired  by 
the  use  of  stronger  eye  pieces. 

Resolving  power  is  the  capability  an  instrument  has  of 
bringing  out  the  fine  details  of  a  structure,  and  depends 
mainly  on  the  angle  of  aperture  of  the  objective,  or  the 
angle  formed  by  the  focus  and  the  extremities  of  the 
diameter  of  the  lens.  On  this  account  the  increase  of  the 
angle  of  aperture  has  been  a  chief  aim  with  practical 
opticians. 

Penetrating  power  is  the  degree  of  distinctness  with 
which  the  parts  of  an  object  lying  a  little  out  of  focus 
may  be  seen.  Objectives  which  have  a  large  angle  of 
aperture,  and  in  consequence  great  resolving  power,  are 
often  defective  in  penetration,  their  very  perfection  only 
permitting  accurate  vision  of  what  is  actually  in  focus. 
Hence  for  general  purposes  a  moderate  degree  of  angular 
aperture  is  desirable. 

Flatness  of  field  of  view  is  also  a  necessity  for  accurate 
observation.  Many  inferior  microscopes  hide  their  im- 
perfection in  this  respect  by  a  contracted  aperture  in  the 
eye-piece,  by  which,  of  course,  only  a  part  of  the  rays 
transmitted  by -the  objective  are  available. 

Object-glasses  whose  focal  length  is  greater  than  half 
an  inch  are  called  low  powers.  Medium  powers  range 
from  one-half  to  one-fifth  of  an  inch  focal  length,  and  all 
objectives  less  than  one-fifth  are  considered  high  powers. 

For  definition  with  low  power  objectives,  the  pollen 
grains  of  hollyhock,  or  the  tongue  of  a  fly,  or  a  specimen 
of  injected  animal  tissue,  will  be  a  sufficient  test.  The 
aperture  should  be  enough  to  give  a  bright  image,  and 
the  definition  sufficient  for  a  clear  image.  A  section  of 
wood,  or  of  an  echinus  spine,  will  test  the  flatness  of  the 
field. 

Medium  powers  are  seldom  used  with  opaque  objects 
unless  they  are  very  small,  but  are  most  useful  with 


56  THE    MICROSCOPIST. 

properly  prepared  transparent  objects.  A  good  half-inch 
objective  should  show  the  transverse  markings  between 
the  longitudinal  ribs  on  the  scales  of  the  Hipparcliia 
janira,  butterfly  (Plate  I,  Fig.  27),  and  the  one-fourth  or 
one-fifth  should  exhibit  markings  like  exclamation  points 
on  the  smaller  scales  of  Podura  plumbea  (Plate  I,  Fig.  28) 
or  Lepidocyrtis. 

High  power  objectives  are  chiefly  used  for  the  most 
delicate  and  refined  investigations  of  structure,  and  are 
not  so  suitable  for  general  work.  It  is  with  these  glasses 
that  angular  aperture  is  so  necessary  to  bring  out  striae, 
and  dots,  and  other  delicate  structures,  under  oblique 
illumination.  For  these  glasses,  the  best  tests  are  the 
siliceous  envelopes  of  diatoms,  as  the  Pleurosigma  angu- 
latum,  Surirella  gemma,  Grammataphora  subtilissima ;  or 
the  wonderful  plates  of  glass  artificially  ruled  by  M.  Ro- 
bert, and  known  as  Nobert's  test. 

The  latter  test  is  a  series  of  lines  in  bands,  the  distance 
between  the  lines  decreasing  in  each  band,  until  their 
existence  becomes  a  matter  of  faith  rather  than  of  sight, 
since  no  glass  has  ever  revealed  the  most  difficult  of  them. 
The  test  plate  has  nineteen  bands,  and  their  lines  are 
ruled  at  the  following  distances:  Band  1,  y^u^h  °f  a 
Paris  line  (to  an  English  inch  as  .088  to  1.000,  or  as  11  to 
125).  Band2,T5'^th.  Band  3,  ^th.  Band  5, 
Band  9,  ^th.  Band  13,  ^th.  Band  17, 
Band  19,  ^i^th. 

It  is  said  that  Hartnack's  immersion  system  No.  10 
and  oblique  light  has  resolved  the  lines  in  the  15th  band, 
in  which  the  distance  of  lines  is  about  ^To^th  of  an  inch. 

The  surface  markings  of  minute  diatoms  are  also  ex- 
cessively fine.  Those  of  Pleurosigma  formosiim,  being  from 
20  to  32  in  y^^th  of  an  inch  ;  of  P.  hippocampus  and  P. 
attenuatum  about  40 ;  P.  angulatum  46  to  52 ;  Navicula 
rhomboides  60  to  111 ;  and  Amphipleura  pelludda  120  to 
130.  This  latter  has  been  variously  estimated  at  100,000 


PLATE  I 


FIG.  28. 


Scale  of  Hijypnrchia  Janira. 


of  Poilura  plumbea : — A,  large 

O  strongly  marked  scale;  B,  small  scale 
more  faintly  marked;  c,  portion  of  an 
injured  scale,  showing  the  nature  of  the 
markings. 


Fio. 29. 


Ple.uro.ngmn  artgulntum : — A,  entire  frustule,  as  seen 
under  a  power  of  500  diam.;  B,  hexagonal  aerolation, 
as  seen  under  a  power  of  1300  diam.;  c,  the  same, 
as  seen  under  a  power  of  15,000  dinm. 


USE    OF    THE    MICROSCOPE. 


57 


to  130,000  in  an  inch.  It  has  been  resolved  by  Dr.  Wood- 
ward with  the  j'gth  immersion  of  Powell  and  Lealand, 
using  oblique  sunlight  through  a  solution  of  ammonio- 
sulphate  of  copper. 

The  longitudinal  lines  (between  the  transverse)  of  the 

FIG.  30. 


Valve  of  Surirella  Gemma, 
a.  Transverse  ridges.    6.  Longitudinal  lines,    c.  The  same,  resolved  into  areolations. 

/Surirella  gemma  are  estimated  at  30  to  32  in  T^o^n  °f  a 
millimetre,  and  the  markings  on  Grammataphora  subtilis- 
sima  at  32  to  34  in  the  same  distance. 

FIG.  31. 


Grammataphora  Subtilissima. 
a.  Valve.    6.  Transverse  lines. 


J.  D.  Moller  has  produced  a  very  excellent  test-plate, 
containing  twenty  diatoms,  with  descriptions,  according 
to  their  value  as  tests. 


58  THE    MICROSCOPIST. 

The  Pleurosigma  angulatum  (Plate  I,  Fig.  29),  with  suit- 
able power  and  illumination,  should  show  distinct  hexag- 
onal areolations.  The  Surirella  gemma  (Fig.  30)  shows  a 
series  of  fine  transverse  lines  across  the  ridges  which  run 
from  the  edge  to  the  central  line.  The  finest  of  these 
ridges  are  not  always  readily  seen,  and  the  transverse 
ones  are  only  to  be  mastered  by  toil  and  patience. 

The  Grammataphora  subtilissima  (Fig.  31)  shows  trans- 
verse lines  (or  rows  of  dots)  along  the  edge,  and  sometimes 
a  double  series  of  oblique  lines. 


CHAPTER   Y. 

MODERN  METHODS  OF  EXAMINATION. 

MICROSCOPY  does  not  limit  its  researches  to  optical 
enlargement,  but  seeks  to  comprehend  elementary  struc- 
ture, and  its  methods  vary  according  to  the  object  imme- 
diately in  view.  It  may  seek  merely  to  discern  the  form 
or  morphology  of  the  elementary  parts  or  their  peculiar 
functions.  It  may  be  concerned  with  inorganic  forms, 
normal  or  pathological  anatomy,  or  with  physiology. 
Each  department  of  pursuit  will  suggest  some  variation, 
yet  a  general  plan  of  operation  is  possible. 

Coarse,  and  moderately  large  objects,  as  a  small  insect, 
a  piece  of  vegetable  tissue,  etc.,  may  be  observed  by  plac- 
ing it  in  the  forceps,  or  on  the  stage  of  the  instrument, 
under  an  objective  of  low  power,  but  ordinarily  a  consid- 
erable degree  of  preparation  is  needed  in  order  to  acquire 
a  true  idea  of  structure. 

Most  of  the  tissues  to  be  examined  are  in  a  moist  con- 


MODERN  METHODS  OF  EXAMINATION.        59 

dition,  and  many  require  to  be  dissected  or  preserved  in 
fluid.  This  has  much  to  do  with  the  appearance  of  the 
object  in  the  microscope.  If  fibres  or  cells  are  imbedded 
in  connective  tissue  or  in'  fluids,  of  which  the  refractive 
power  is  the  same  as  their  own,  they  cannot  be  perceived 
even  with  the  best  glasses,  and  artificial  means  must  be 
resorted  to  that  they  may  become  visible.  The  refractive 
power  of  different  media  causes  different  appearances. 
Thus  a  glass  rod  lying  in  water  is  easily  seen,  but  in 
Canada  balsam,  whose  refractive  power  is  nearly  the  same 
as  glass,  it  is  barely  seen  as  a  flat  band,  and  in  the  more 
highly  refractive  anise  oil  it  presents  the  appearance  of  a 
cavity  in  the  oil. 

During  life  the  cavities  and  fissures  in  animal  tissues, 
in  consequence  of  the  different  refractive  power  of  their 
contents  and  the  change  which  takes  place  soon  after 
death,  exhibit  a  sharpness  and  softness  of  outline  which 
is  seldom  seen  in  preparations. 

There  are  two  methods  of  microscopic  investigation  or 
of  preparation  preliminary  to  direct  observation:  1.  Me- 
chanical, for  the  separation  and  isolation  of  the  elemen- 
tary parts.  2.  Chemical,  which  dissolve  the  connecting 
material,  or  act  on  it  differently  than  on  other  elements. 

For  minute  dissection  a  great  variety  of  instruments 
have  been  proposed,  but  by  practiced  hands  more  can  be 
accomplished  in  shorter  time  by  simple  means  than  with 
complicated  ones.  Two  or  three  scalpels,  or  small  ana- 
tomical knives,  a  pair  of  small  scissors,  such  as  is  used  in 
operations  on  the  eye,  and  fine-pointed  forceps,  will  be 
found  useful.  But  the  most  serviceable  instruments  are 
dissecting-needles,  such  as  the  microscopist  may  make  for 
himself.  A  common  sewing-needle,  with  the  eye  end 
thrust  into  a  cedar  stick  aboiit  three  inches  long  and  one- 
fourth  of  an  inch  diameter,  will  answer  the  purpose.  The 
point  should  not  project  so  far  as  to  spring,  and  if  desired, 
a  cutting  edge  can  be  given  to  it  by  a  hone. 


60 


THE    MICROSCOPIST. 


The  light  should  be  concentrated  on  the  work  by  means 
of  a  bull's-eye  condenser,  and  as  far  as  possible,  the  dis- 
section should  be  carried  on  with  the  unassisted  eye. 
Very  often  the  work  is  so  fine  that  a  magnifying  glass, 
or  simple  microscope,  fixed  to  a  suitable  arm,  will  be 
needed.  A  large  Coddington  lens,  an  inch  and  a  half  in 
diameter,  such  as  is  used  frequently  by  miners,  will  be 
useful.  Sometimes  it  is  necessary  to  resort  to  the  dissect- 
ing microscope,  which  is  a  simple  lens,  of  greater  or  less 
power,  arranged  with  rack  and  pinion,  mirror,  etc. 

The  specimen  may  be  dissected  under  water,  in  a  glass 
or  porcelain  dish,  or  a  trough  made  of  gutta-percha,  etc. 
Dr.  Lawson's  binocular  dissecting  microscope  (Fig.  32)  is 

FIG.  32. 


Lawson's  Binocular  Dissecting  Microscope. 


a  most  useful  form,  as  both  eyes  may  be  used.  Loaded 
corks,  with  sheet  lead  fastened  to  their  under  surface, 
may  be  used  to  pin  the  subject  on  for  greater  facility  in 
dissection.  Rests,  or  inclined  planes  of  wood,  one  on  each 
side  of  the  trough,  will  give  steadiness  to  the  hands. 
Camels'-hair  pencils  for  the  removal  of  dust  and  extrane- 


MODERN    METHODS    OP    EXAMINATION.  61 

ous  elements,  and  for  spreading  out  thin  and  delicate  tis- 
sues or  sections,  are  indispensable.  Pipettes,  or  glass 
tubes,  one  end  of  which  can  be  covered  with  the  end  of 
the  finger,  may  serve  to  convey  a  drop  of  fluid  or  a  small 
specimen  from  a  bottle. 

Preparation  of  Loose  Textures. — If  the  formed  elements 
of  tissue  do  not  combine  in  a  solid  mass,  it  is  only  neces- 
sary to  place  a  small  quantity  on  a  glass  slide  and  cover 
it  with  a  plate  of  thin  glass.  If  the  elements  are  too  close 
for  clear  definition  under  the  microscope,  a  drop  of  fluid 
may  be  added.  The  nature  of  this  fluid,  however,  is  not 
a  matter  of  indifference.  Some  elements  are  greatly 
changed  by  water,  etc.,  and  it  becomes  important  to  con- 
sider the  fluid  which  is  most  indifferent.  Glycerin  and 
water,  one  part  to  nine  of  water,  will  serve  well  for  most 
objects.  Animal  tissues  are  often  best  treated  with  aque- 
ous humor,  serum,  or  iodized  serum.  A  weak  solution  of 
salt,  7.5  grains  chloride  of  sodium  to  1000  grains  of  dis- 
tilled water,  serves  for  many  delicate  structures.  (See 
section  on  Fluid  Media.} 

Preparation  by  Teasing. — A  minute  fragment  of  tissue 
should  be  placed  in  a  drop  of  fluid  on  a  slide,  and  torn  or 
unravelled  by  two  sharp  needles.  This  is  accomplished 
more  easily  after  maceration,  and  sometimes  it  is  neces- 
sary to  macerate  in  a  substance  which  will  dissolve  the 
connecting  material.  This  picking  or  teasing  should  be 
slowly  and  accurately  performed.  Beginners  often  fail 
of  a  good  preparation  by  ceasing  too  soon,  as  well  as  by 
having  too  large  a  specimen.  The  most  delicate  manipu- 
lation is  required  to  isolate  nerve-cells  and  processes. 

Preparation  by  Section. — A  section  of  soft  substance  may 
be  made  with  a  sharp  knife  or  scalpel,  or  with  a  pair  of 
scissors  curved  on  the  upper  side.  A  section  cut  with  the 
latter  will  taper  away  at  the  edges  so  as  to  aflbrd  a  view 
of  its  structure. 


62  THE    MICROSCOPIST. 

Valentin's  double  knife  (Fig.  33)  is  used  for  soft  tissues 
where  only  a  moderate  degree  of  thinness  is  needed.  The 
blades  should  be  wet,  or  the  section  made  under  water. 

Soft  substances  often  require  hardening  before  sections 
can  be  made.  The  most  simple  and  best  method  is  that 
of  freezing,  by  surrounding  the  specimen  with  a  freezing 
mixture,  when  it  may  be  cut  with  a  cold  knife.  Small 
pieces  of  tissue  may  be  hardened  in  absolute  alcohol,  fre- 
quently renewed.  Chromic  acid,  in  solution  of  one-fourth 
to  two  per  cent.,  is  often  used  for  animal  tissues,  or  bichro- 
mate of  potash  of  the  same  strength.  A  solution  of  one- 
fifth  to  one-tenth  per  cent,  of  perosmic  acid  or  of  chloride 
of  palladium  is  also  recommended. 

Soft  tissues  often  require  imbedding  in  a  concentrated 
solution  of  gum  or  of  wax,  spermaceti,  or  paraffin  tem- 
pered with  oil.  In  this  case  sections  may  be  made  readily 
by  means  of  a  section-cutter.  For  imbedding  in  wax,  etc., 

FIG.  33. 


Valentin's  Knife. 

the  specimen  must  be  hardened  in  alcohol,  then  treated 
with  oil  of  cloves  or  turpentine,  and  the  section  should  be 
mounted  in  Canada  balsam  or  Dammar  varnish. 

Sections  of  hard  substances,  or  of  those  imbedded,  are 
often  made  by  machines  invented  for  the  purpose.  One 
of  the  simplest  is  (Fig.  34)  an  upright  hollow  cylinder, 
with  a  kind  of  piston,  pushed  upwards  by  a  fine  screw. 
The  upper  end  of  the  cylinder  carrying  the  specimen  ter- 
minates in  a  flat  table,  along  which  a  sharp  knife  or  flat 
razor  is  made  to  slide.  At  one  side  of  the  tube  is  a 
binding-screw  for  holding  the  specimen  steady.  A  sec- 


MODERN  METHODS  OF  EXAMINATION.        63 

tion  may  be  cut  by  such  an  instrument  after  inserting 
the  structure  desired  in  a  piece  of  carrot,  etc.,  which  may 
be  placed  in  the  tube ;  or  the  tube  may  be  filled  with  wax, 
etc.,  and  the  specimen  imbedded.  Bones,  teeth,  shells, 
corals,  minerals,  etc.,  require  to  be  cut  with  fine  saws,  or 
a  disk  of  thin  iron  on  a  lapidary's  wheel,  and  filed  or 
ground  down  to  the  requisite  thinness,  then  polished  with 
emery,  rouge,  etc.  The  green  oxide  of  chromium  has 
been  suggested  to  me  as  a  useful  polishing  powder  for 
hard  substances.  For  calcareous  substances,  files  and 
hones  will  suffice  to  reduce  the  thickness,  and  putty 

FIG.  34. 


Section-Cutter. 

powder  or  jewellers'  rouge  for  polishing.     They  should 
be  mounted  in  Canada  balsam. 

Staining  Tissues. — Certain  elements,  not  previously  visi- 
ble, can  often  be  made  evident  by  certain  coloring  matters, 
by  which  some  constituents  become  more  quickly  or  more 
thoroughly  stained  than  others.  The  "  germinal  matter," 
or  "bioplasm"  of  Dr.  Beale,  identical  with  the  "proto- 
plasm "  or  "  sarcode  "  of  other  observers,  may  thus  be  dis- 
tinguished from  the  "  formed  materials  "  or  "  tissue  ele- 


64 


THE    MICROSCOPIST. 


ment,"  which  are  the  products  of  its  activity.  Carmine, 
anilin,  haematoxylin,  and  picric  acid,  are  used  for  staining 
by  imparting  their  own  color  to  tissues ;  while  nitrate  of 
silver,  chloride  of  gold,  chloride  of  palladium,  and  peros- 
mic  acid  stain,  by  their  chemical  action,  often  under  the 
reducing  influence  of  light.  (See  Fluid  Media.} 

Injecting  Tissues. — Injections  of  the  vessels  in  animal 
tissues  are  resorted  to  either  to  exhibit  their  course  or  the 
structure  of  the  vascular  walls.  For  the  latter  purpose  a 
solution  of  nitrate  of  silver  is  commonly  employed,  for  the 
former  either  opaque  or  transparent  coloring  matter.  (See 
Fluid  Media.} 

The  injecting  syringe  (Fig.  35)  is  made  of  brass  or  Ger- 


FIG.  35. 


Injecting  Syringe. 

man  silver.  One  of  the  pipes  should  be  inserted  into  the 
principal  vessel,  as  the  aorta  of  a  small  animal,  the  um- 
bilical vein  of  a  foetus,  or  the  artery,  etc  ,  of  an  organ, 
and  should  be  securely  fastened  by  a  thread.  All  other 
open  vessels  should  be  tied.  The  solution  of  gelatin,  or 
other  matter  used,  should  be  strained,  so  as  to  be  free 
from  foreign  particles,  and  should  be  forced  into  the  ves- 
sels with  a  gentle,  steady  pressure  on  the  syringe. 

Injections  should  be  made  soon  after  the  death  of  the 
animal,  or  else  after  the  rigor  mortis  has  subsided. 


MODERN    METHODS    OF    EXAMINATION.  65 

Sometimes  the  syringe  is  substituted  by  a  self-acting 
apparatus,  consisting  of  a  Wolfe's  bottle,  containing  the 
fluid,  which  is  pressed  upon  by  a  column  of  air  from 
another  source,  and  driven  through  a  flexible  tube  to  the 
pipe  in  the  bloodvessel. 

The  older  anatomists  used  colored  plaster  or  wax  to 
demonstrate  the  arteries  and  veins,  but  modern  histology 
requires  finer  materials.  Isinglass  or  gelatin,  colored,  and 
injected  warm,  or  a  solution  of  colored  glycerin,  are  now 
resorted  to.  The  former  serves  for  opaque,  and  the  latter 
for  fine,  transparent  injections. 

The  art  of  injecting  can  only  be  learned  by  practice, 
yet  perseverance,  in  despite  of  many  failures,  will  insure 
success. 

The  liver,  kidney,  etc.,  may  be  injected  separately,  and 
it  is  often  desirable  to  use  various  colors  for  the  different 
sets  of  vessels.  After  injection  thin  slices  may  be  cut  off 
and  mounted  in  fluid  or  balsam. 

Preparation  in  Viscid  Media. — Dr.  Beale  has  proposed  a 
method  of  preparing  animal  and  vegetable  tissues  for  -ex- 
amination with  the  very  highest  powers,  which  has  led  to 
valuable  results.  It  consists  in  using  pure  glycerin  or 
strong  syrup,  instead  of  watery  solutions.  In  this  way 
an  amount  of  pressure  may  be  applied  to  sections,  in  order 
to  render  them  thin  enough  for  examination,  which  would 
be  destructive  to  specimens  in  water,  while  the  preserva- 
tive action  of  the  media  prevents  change  in  the  structure. 
It  is  necessary  to  soak  the  specimen  some  time,  and  the 
strength  of  the  fluid  should  be  gradually  increased  until 
the  tissue  is  permeated  by  the  strongest  that  can  be  ob- 
tained. Dr.  Beale  has  found  that  minute  dissection  is 
much  more  readily  performed  in  such  fluids,  and  that 
even  very  hard  textures,  as  bone  and  teeth,  may  be  softened 
by  them,  especially  if  acetic  acid  is  added,  so  as  to  permit 
thin  sections  to  be  made  with  a  knife.  He  recommends 


66  THE    MICROSCOPIST. 

vessels  to  be  first  injected,  as  with  fine,  transparent  blue, 
and  the  germinal  matter  to  be  stained  with  carmine.  A 
few  drops  of  a  solution  of  chromic  acid,  or  bichromate  of 
potash,  so  as  to  impart  to  the  glycerin  a  pale  straw  color, 
serves  to  harden  even  the  finest  nerve-structures.  Acetic 
acid,  and  other  reagents  also,  are  much  more  satisfactorily 
used  with  glycerin  than  with  water.  If  syrup  is  used, 
camphor,  carbolic  acid,  etc  ,  must  be  employed  to  prevent 
the  growth  of  fungi,  but  pure  glycerin  is  free  from  this 
inconvenience. 

A  great  advantage  of  this  mode  of  investigation  con- 
sists in  the  fact  that  a  specimen  thus  prepared  is  already 
mounted,  and  needs  but  a  proper  cement  to  the  glass  cover 
and  a  finish  to  the  slide,  when  it  is  ready  for  the  cabinet. 


FLUID  MEDIA. 
1.  INDIFFERENT  FLUIDS. 

The  vitreous  humor,  amniotic  liquor,  serum,  etc.,  which 
form  the  usual  fluids  termed  indifferent,  always  contain 
what  Prof.  Graham  designated  colloid  and  crystalloid 
substances.  In  1 000  parts  there  are  about  4  parts  of  col- 
loid (albumen)  and  7.5  of  crystalloid  substance  (chloride 
of  sodium). 

The  iodine  serum  of  Schultze  consists  of  the  amniotic 
fluid  of  the  embryo  of  a  ruminant,  to  which  about  6  drops 
of  tincture  of  iodine  to  the  ounce  is  added  A  small  piece 
of  camphor  will  preserve  this  from  decomposition  a  long 
time.  A  substitute  for  this  is  composed  of  1  ounce  of 
white  of  egg,  9  ounces  of  water,  2  scruples  chloride  of 
sodium,  with  the  corresponding  quantity  of  tincture  of 
iodine. 


MODERN    METHODS    OF    EXAMINATION.  6? 

'&J.. 

,        /r 

2.  CHEMICAL  REAGENTS'. 

The  greatest  care  should  be  used  with  these,  that  the 
instrument  and  glasses  maybe  preserved.  A  small  drop, 
applied  by  a  glass  rod  drawn  out  to  a  point  to  the  edge  of 
the  glass  cover,  will  suffice  in  most  cases, 

Sulphuric  Add. — Concentrated  is  used  to  isolate  the 
cells  of  horny  structures,  as  hair,  nails,  etc.  Dilute  (1  part 
to  2-3  of  water)  gives  to  cellulose,  previously  dyed  with 
iodine,  a  blue  or  purple  color,  and,  when  mixed  with 
sugar,  a  rose-red  to  nitrogenous  substances  and  bile.  0.1 
to  1000  of  water,  at  a  temperature  of  35-40°  C.,  resolves* 
connective  tissue  into  gelatin  and  dissolves  it,  so  as  to  be 
useful  in  isolating  muscular  fibres. 

Nitric  Acid. — Diluted  with  4  or  5  parts  water,  separates 
the  elementary  parts  of  many  vegetable  and  animal  tis- 
sues when  they  are  boiled  or  macerated  in  it.  With  chlo- 
rate of  potash  it  is  still  more  energetic,  but  caution  is 
needed  in  its, use. 

Muriatic  Acid,  Strong. — Used  for  dissolving  intercellular 
substance,  as  in  the  tubes  of  the  kidney,  etc.  Dilute  for 
dissolving  calcareous  matter. 

Chromic  acid,  J  to  2  per  cent,  solution  for  hardening 
nerves,  brain,  etc. 

Oxalic  acid,  to  15  parts  water,  causes  connective  tissue 
to  swell  and  become  transparent,  while  albuminoid  ele- 
ments are  hardened.  Preserves  well  delicate  substances, 
as  rods  of  retina,  etc. 

Acetic  acid  makes  nuclei  visible  and  connective  tissue 
transparent,  so  as  to  exhibit  muscles,  nerves,  etc.,  other- 
wise invisible. 

Iodine  (1  grain  of  iodine,  3  grains  iodide  of  potassium, 
1  ounce  of  water)  turns  starch  blue  and  cellulose  brown. 

Caustic  potash  or  soda  renders  many  structures  trans- 
parent. 


68  THE    MICROSCOPIST. 

Lime-water  or  baryta-water  is  used  for  investigating  con- 
nective structures,  especially  tendon,  as  maceration  en- 
ables the  needle  to  divide  its  fibrilla. 

Chloride  of  Sodium. — Solutions  of  this  salt  for  indifferent 
media  should  always  have  some  colloid,  as  albumen  or 
gum-arabic  added  (7.5  grains  in  1000  grains  of  water  for 
delicate  structures). 

Bichromate  of  potash  is  used  in  stronger  solution  for  the 
same  purposes  as  chromic  acid. 

Miiller  *s  eye-fluid  for  hardening  the  retina,  and  preserv- 
ing delicate  embryos,  etc.,  consists  of  bichromate  of  potass,, 
2  grammes  ;  sulphate  of  soda,  1  gramme  ;  distilled  water, 
100  grammes. 

Alcohol  dissolves  resins  and  many  vegetable  coloring 
matters  ;  renders  most  vegetable  preparations  more  trans- 
parent, and  albuminous  animal  tissues  more  opaque. 

Acetic  acid  and  alcohol,  1  part  of  each  to  2  of  water, 
renders  connective  tissue  transparent,  and  albuminoid  tis- 
sue prominent.  The  proportions  can  be  varied. 

Alcohol  and  soda  (8-10  drops  of  strong  solution  of  caustic 
soda  to  each  ounce)  renders  many  tissues  very  hard  and 
transparent.  Beale  recommends  it  for  embryonic  struc- 
tures. 

Ether  dissolves  resins,  oils,  and  fat. 

Turpentine  renders  dried  animal  sections  transparent. 

Oil  of  cloves  acts  as  turpentine. 

Solution  of  chloride  of  zinc,  iodine,  and  iodide  of  potassium, 
is  recommended  by  Schacht  as  a  substitute  for  iodine  and 
sulphuric  acid  to  color  vegetable  cells,  etc.  Zinc  is  dis- 
solved in  hydrochloric  acid,  and  the  solution  is  evaporated 
to  syrupy  consistence  in  contact  with  metallic  zinc.  This 
is  saturated  with  iodide  of  potassium,  iodine  added,  and 
the  solution  diluted  with  water.  Wood  cells,  after  boiling 
in  caustic  potash,  are  stained  blue  by  it. 

Boracic  acid,  used  by  Prof.  Brucke  to  separate  the  ele- 
ments of  red  blood-corpuscles. 


MODERN  METHODS  OF  EXAMINATION.  69 

3.  STAINING  FLUIDS. 

Thiersch's  Carmine  Fluids. 

a.  RED  FLUID. 

1.  Carmine,     .         .  .         .  .         .       1  part. 

Caustic  ammonia,  .  ••*>  "...  '.,'-...       1     " 

Distilled  water,  .  .  .        .        .       3  parts.     Filter. 

2.  Oxalic  acid,         .  .  .  .•       .         .       1  part. 
Distilled  water,  .  *  »  -v        .        .  22  parts. 

1  part  of  carmine  solution  to  8  parts  of  the  acid  solution,  add  12  parts 
absolute  alcohol.  Filter.  After  staining  wash  in  80  per  cent,  alcohol. 

b.  LILAC  FLUID. 

Borax,        ,        •  ...-..       •        •        •        •       4  parts. 

Distilled  water,  .        .        .         .     *  .        .     56    " 
Dissolve  and  add, 

Carmine,   .         .         .         .         .       '.-.'•       1  part. 
Mix  with  twice  the  volume  of  absolute  alcohol  and  filter. 

Beetle's  Carmine  Fluids. 

Carmine,  .         .         .         .         .  .10  grains. 

Strong  liquor  ammonia,    .         .   '     .         .       \  drachm. 
Glycerin,  ....        .        .    *  " .      2  ounces. 

Distilled  water,         .        .  •'    -.'       v        .       2      "      '    i 
Alcohol,    .         .         .        ..  -      ,        .  \  ounce. 

Dissolve  the  carmine  in  the  ammonia  in  a  test-tube  by  aid  of  heat ;  boil 
it  and  cool  and  add  the  other  ingredients.  Filter. 

Acid  Carmine  Fluid. — Mix  ammoniacal  solution  of  car- 
mine with  acetic  acid  in  excess  and  filter.  This  is  said 
to  stain  diffusely,  but  adding  glycerin  with  muriatic  acid 
(1 :  200),  concentrates  the  color  in  the  cell-nucleus. 

Anilin  (or  Magenta)  Red  Fluid. 

Fuchsin  (crystal), 1  centigramme. 

Absolute  alcohol, 20-25  drops. 

Distilled  water,        .....     15  cubic  centim. 

Anilin  Blue  Fluid. — Anilin  blue,  treated  with  sulphuric 
acid  and  dissolved  in  water  till  a  deep  cobalt  color  is 
obtained. 


70  THE    MICROSCOPIST. 

Blue  Fluid  from  Indigo  Carmine. 

Oxalic  acid, 1  part. 

Distilled  water, 20-30  parts. 

Indigo  carmine  to  saturation. 

Logwood  Violet  Fluid. 

1.  Haematoxylin,    ......     20  grains. 

Absolute  alcohol, $  ounce. 

2.  Solution  of  2  grains  of  alum  to  1  ounce  of  water. 

A  few  drops  of  the  first  solution  to  a  little  of  the  second  in  a  watch- 
•glass,  etc. 

Picro-Carmine  Fluid.  —  Filter  a  saturated  solution  of 
picric  acid,  and  add,  drop  by  drop,  strong  ammoniacal 
solution  of  carmine  till  neutralized. 

Nitrate  of  Silver  Fluid. — Fresh  membranous  tissues, 
exposed  to  0.5  to  0.2  per  cent,  solution  of  nitrate  of  silver, 
washed  and  exposed  to  light,  often  show  a  mosaic  of  epi- 
thelium, etc. 

Osmic  Acid. — y^th  to  1  per  cent,  solution  stains  the 
medulla  of  nerves,  etc.,  black. 

Chloride  of  Gold. — The  solution  should  be  similar  to  that 
of  nitrate  of  silver.  Exposure  to  light  stains  the  nerves, 
etc.,  a  violet  or  red  color. 

Prussian  Blue. — After  immersing  a  tissue  in  0.5  to  1 
per  cent,  solution  of  a  protosalt  of  iron,  dip  it  in  a  1  per 
cent,  solution  of  ferrocyanide  of  potassium. 

Other  Staining  Fluids. — Marked  effects  are  often  pro- 
duced by  the  use  of  the  violet,  blue,  and  other  inks  in  the 
market.  Thus  I  succeeded  in  some  demonstrations  of 
nerve  plexuses  in  muscle  better  than  in  any  other  way. 
I  suspect  the  particular  ink  employed  contained  a  large 
per  cent,  of  soluble  Prussian  blue. 

4.  INJECTING  FLUIDS. 

For  opaque  injection  several  plans  have  been  devised. 
Resinous  and  gelatinous  substances,  variously  colored,  are 


MODERN  METHODS  OP  EXAMINATION.        71 

most  usual.  Lieberkuhn  used  tallow,  varnish,  and  tur- 
pentine, colored  with  cinnabar  ;  and  Hyrtl,  whose  prepa- 
rations have  been  much  admired,  follows  a  similar  plan. 
He  evaporates  pure  copal  or  mastic  varnish  to  the  consis- 
tence of  syrup,  and  grinds  one-eighth  as  much  cinnabar 
and  a  little  wax  with  it  on  a  slab.  For  fine  injections  this 
is  diluted  with  ether. 

For  a  bright  red,  the  cinnabar  may  be  mixed  with  a 
little  carmine 

For  a  yellow  color,  the  chromate  of  lead,  prepared  by 
mixing  solutions  of  acetate  of  lead  (36  parts  to  2  ounces 
of  water),  and  red  chromate  of  potash  (15  parts). 

White  may  be  made  with  zinc-white  or  carbonate  of 
lead — 4J  ounces  of  acetate  of  lead  in  16  ounces  of  water, 
mixed  with  3  J  ounces  carbonate  of  soda  in  16  ounces. 

For  gelatinous  injections  the  coloring  matter  is  com- 
bined with  jelly,  prepared  by  soaking  fine  gelatin  in  cold 
water  for  several  hours,  then  dissolving  in  a  water-bath 
and  filtering  through  flannel. 

By  injecting  gelatinous  fluid  solutions  of  various  salts, 
the  coloring  matter  may  be  left  in  the  vessels  by  double 
decomposition. 

A  red  precipitate,  with  iodide  of  potassium  and  bichlo- 
ride of  mercury. 

A  blue,  by  ferrocyanide  of  potassium  and  peroxide  of 
iron,  etc. 

Dr.  Goadby's  formula  for  a  yellow  color  is : 

Saturated  solution  of  bichromate  of  potassium,  .     8  ounces. 

Water, 8       " 

Gelatin,        .         .         .  .         .         .         .     2       " 

Saturated  solution  of  acetate  of  lead,  .        .         .8  ounces. 
"Water,         ........     8       " 

Gelatin, 2       " 

For  gelatinous  injections,  both  the  fluid  and  the  subject 
should  be  as  warm  as  may  consist  with  convenience. 
Camphor  also  should  be  added  to  prevent  mould. 


72  THE    MICROSCOPIST. 

For  transparent  injections,  gelatin  may  be  used  combined 
with  colored  solutions,  or  still  better,  glycerin,  which  may 
be  used  cold. 

ThierscKs  Blue. — Half  an  ounce  of  warm  concentrated 
solution  (2:1)  of  fine  gelatin  is  mixed  with  6  cubic  centim- 
etres of  a  saturated  solution  of  sulphate  of  iron.  In 
another  vessel,  1  ounce  of  the  gelatin  solution  is  mixed 
with  12  cubic  centimetres  of  saturated  solution  of  ferro- 
cyanide  of  potassium,  to  which  12  cubic  centimetres  of 
saturated  solution  of  oxalic  acid  is  added.  When  cold, 
add  the  gelatinous  solution  of  sulphate  of  iron  drop  by 
drop,  with  constant  stirring,  to  the  other.  Warm  it, 
still  stirring,  and  filter  through  flannel. 

Gerlach's  Carmine. — Dissolve  5  grammes  (77  grains)  of 
fine  carmine  in  4  grammes  (70  grains)  of  water  and  J 
gramme  (8  drops)  of  liquor  ammonia.  Let  it  stand  sev- 
eral days  (not  airtight),  and  mix  with  a  solution  of  6 
grammes  of  fine  gelatin  to  8  grammes  of  water,  to  which 
a  few  drops  of  acetic  acid  are  added. 

Thiersch's  Yellow. — Prepare  a  solution  of  chromate  of 
potash  (1 : 11),  and  a  second  solution  of  nitrate  of  lead,  of 
same  strength.  To  1  part  of  the  first  add  4  parts  of  solu- 
tion of  gelatin  (about  20  cubic  centimetres  to  80),  and  to 
2  parts  of  the  second  add  4  parts  of  gelatin  (40  cubic  cen- 
timetres to  80).  Mix  slowly  and  carefully,  heat  on  a 
water-bath,  and  filter  through  flannel. 

Equal  parts  of  Thiersch's  blue  and  yellow  carefully 
mixed  and  filtered  make,  a  good  green. 

COLD   TRANSPARENT   INJECTIONS. 

Beale's  Blue. 

Glycerin, .         .         .         .         ...         .         .1  ounce. 

Alcohol,  .        .        ..'.,.     .  .        .        .1      " 

Ferrocyanide  of  potassium,      ....     12  grains. 
Tincture  of  perchloride  of  iron,        .        .        .       1  drachm. 
Water,     .         .         .,      ».     .  ..,     ;»        •         •      4  ounces. 


MODERN    METHODS    OF    EXAMINATION.  73 

Dissolve  the  ferrocyanide  in  1  ounce  of  water  and  glyc- 
erin, and  the  muriated  tincture  of  iron  in  another  ounce. 
Add  the  latter  very  gradually  to  the  other,  shaking  often ; 
then  gradually  add  the  alcohol  and  water. 

Scale's  Finest  Blue. 

Price's  glycerin,         .         .         .         .         .        «  2  ounces. 

Tincture  of  perchloride  of  iron,          .         .         .  10  drops. 

Ferrocyanide  of  potassium,        .         .  .  3  grains. 

Strong  hydrochloric  acid, .....  8  drops. 

Water, 1  ounce. 

Mix  the  tincture  of  iron  with  1  ounce  glycerin  and  the 
ferrocyanide,  after  dissolving  in  a  little  water,  with  the 
other  ounce.  Add  the  iron  to  the  other  solution  gradu- 
ally, shaking  well.  Lastly,  add  the  water  and  hydro- 
chloric acid.  Sometimes  about  2  drachms  of  alcohol  are 
added. 

Mutter's  Blue. — This  is  made  by  precipitation  of  soluble 
Prussian  blue  from  a  concentrated  solution  by  means  of 
90  per  cent,  alcohol. 

Beetle's  Carmine. — Mix  5  grains  of  carmine  with  a  few 
drops  of  water,  and  when  well  incorporated,  add  5  or  6 
drops  of  liquor  ammonia.  To  this  add  J  ounce  of  glyc- 
erin, and  shake  well.  Another  J  ounce  of  glycerin  con- 
taining 8  or  10  drops  of  acetic  or  hydrochloric  acid  is 
gradually  added.  It  is  then  diluted  with  J  ounce  of  glyc- 
erin, 2  drachms  of  alcohol,  and  6  drachms  of  water. 

Nitrate  of  Silver  Injection. — For  demonstrating  the  struc- 
ture of  the  bloodvessels,  the  animal  is  bled,  and  a  solution 
of  0.25  to  1  per  cent,  of  nitrate  of  silver,  or  a  mixture  of 
gelatin  with  such  a  solution,  is  used. 

5.  PRESERVATIVE  FLUIDS. 

Canada  Balsam. — This  is  perhaps  the  most  common 
medium  used.  When  an  object  is  not  very  transparent, 
and  drying  will  not  injure  it,  balsam  will  do  very  well, 


74  THE    MICROSCOPIST. 

but  it  is  not  adapted  to  moist  preparations.  Colonel 
Woodward,  of  Washington,  uses  a  solution  of  dried  or 
evaporated  Canada  balsam  in  chloroform  or  benzole. 

Dammar  Varnish. — Dr.  Klein  and  other  German  his- 
tologists  prefers  this  to -Canada  balsam.  Dissolve  J  to  1 
ounce  of  gum  Dammar  in  1  ounce  of  turpentine ;  also  J 
to  1  ounce  *of  mastic  in  2  ounces  of  chloroform.  Mix  and 
filter. 

Glycerin. — This  fluid  is  universally  useful  to  the  micros- 
copist.  (See  Preparation  in  Viscid  Media,  page  65.)  Vege- 
table and  animal  substances  may  be  preserved  in  glycerin, 
but  if  it  is  diluted,  camphor  or  creasote  must  be  added 
to  prevent  confervoid  growths.  It  is  said,  however,  to 
dissolve  carbonate  of  lime. 

Gelatin  and  Glycerin. — Soak  gelatin  in  cold  water  till 
soft,  then  melt  in  warm  water,  and  add  an  equal  quantity 
of  glycerin. 

Gum  and  Glycerin. — Dissolve  1J  grains  of  arsenious 
acid  in  1  ounce  of  wafer,  then  1  ounce  of  pure  gum  arabic 
(without  heat),  and  add  1  ounce  of  glycerin. 

Deane's  Compound. — Soak  1  ounce  of  gelatin  in  5  ounces 
of  water  till  soft ;  add  5  ounces  of  honey  at  a  boiling  heat. 
Boil  the  mixture,  and  when  cool,  add  <5  drops  of  creasote 
in  J  ounce  of  alcohol;  filter  through  flannel.  To  be  used 
warm. 

Carbolic  Acid. — 1 : 100  of  water  is  a  good  preservative. 

Thwaite's  Fluid.— To  16  parts  of  distilled  water,  add  1 
part  of  rectified  spirit  and  a  few  drops  of  creasote ;  stir  in 
a  little  prepared  chalk,  and  filter.  Mix  an  equal  measure 
of  camphor-water,  and  strain  before  using.  For  preserva- 
tion of  algse. 

Solution  of  Naphtha  and  Creasote. — Mix  3  drachms  of 
creasote  with  6  ounces  of  wood  naphtha ;  make  a  thick, 
smooth  paste  with  prepared  chalk,  and  add  gradually, 
rubbing  in  a  mortar,  64  ounces  of  water.  Add  a  few 
lumps  of  camphor,  and  let  it  stand  several  weeks  before 


MODERN  METHODS  OF  EXAMINATION.        75 

pouring  off  or  filtering  the  clear  fluid.  Dr.  Beale  recom- 
mends this  highly  for  the  preservation  of  dissections  of 
nerves  and  morbid  specimens. 

Ealfs  Fluid. — As  a  substitute  for  Thwaite's  fluid  in 
the  preservation  of  algae.  1  grain  of  alum  and  1  of  bay 
salt  to  1  ounce  of  distilled  water. 

G oadln/s  Solution. — Bay  salt,  4  ounces;  alum-, 2  ounces; 
corrosive  sublimate,  4  grains;  boiling  water,  4  pints. 
This  is  the  strength  most  generally  useful,  although  it 
may  be  made  stronger  or  more  dilute.  It  is  a  useful 
fluid.  If  the  specimen  contain  carbonate  of  lime,  the 
alum  must  be  left  out,  and  the  quantity  of  salt  may  be 
quadrupled. 

Dr.  Beale  discards  all  solutions  containing  salts  for 
microscopic  purposes,  as  they  render  the  textures  opaque 
and  granular. 

Soluble  Glass,  or  a  solution  of  silicate  of  soda  or  potash, 
or  of  both,  has  been  proposed,  but  it  is  apt  to  render 
specimens  opaque. 

Chloride  of  Calcium  in  saturated  aqueous  solution  has 
been  much  recommended,  especially  by  botanists. 

Acetate  of  Potash,  a  nearly  saturated  solution,  is  useful 
for  vegetable  preparations  and  for  specimens  of  animal 
tissue  which  have  been  stained  with  osmic  acid.  The 
latter  do  not  bear  glycerin. 

Pacinian  Fluid. — This  is  variously  modified,  but  may 
consist  of  corrosive  sublimate,!  part;  chloride  of  sodium, 
2  parts;  glycerin,  13  parts;  distilled  water,  113  parts. 
Sometimes  acetic  acid  is  substituted  for  chloride  of  so- 
dium. 

6.  CEMENTS. 

Gold  Size  is  recommended  by  Dr.  Carpenter  as  most 
generally  useful  for  thin  covers.  It  is  made  by  boiling 
25  parts  of  linseed  oil  for  three  hours  with  1  part  of  red 
lead  and  J  of  as  much  umber.  The  fluid  part  is  then 
mixed  with  yellow  ochre  and  white  lead  in  equal  parts, 


76  THE    MICROSCOPIST. 

so  as  to  thicken  it,  the  whole  boiled  again,  and  the  fluid 
poured  off  for  use. 

BelVs  Cement  is  said  to  be  best  for  glycerin  specimens. 
It  appears  to  be  shellac  dissolved  in  strong  alcohol. 

Brunswick  Black  is  asphaltum  dissolved  in  turpentine. 
A  little  india-rubber  dissolved  in  mineral  naphtha  is  some- 
times added. 

Canada  Balsam  in  chloroform  or  Dammar  varnish  (page 
74)  is  often  used  as  a  cement. 

Marine  Glue. — This  is  most  useful  in  building  glass 
cells,  etc.  It  consists  of  equal  parts  of  shellac  and  india- 
rubber  dissolved  in  mineral  naphtha  by  means  of  heat. 

Electrical  Cement  is  made  by  melting  together  5  parts 
of  rosin,  1  of  beeswax,  and  1  of  red  ochre.  2  parts  of 
Canada  balsam  added  make  it  more  adhesive  to  glass. 

White,  hard  Varnish,  or  gum  sandarac,  dissolved  in 
alcohol  and  mixed  with  turpentine  varnish,  is  sometimes 
colored  by  lampblack,  sealing-wax,  etc. 

White  Zinc  Cement. — Oxide  of  zinc  rubbed  up  with 
equal  parts  of  oil  of  turpentine  and  8  parts  of  solution  of 
gum  Dammar  in  turpentine  of  a  syrupy  consistence,  or 
Canada  balsam,  chloroform,  and  oxide  of  zinc. 


CHAPTER   VI. 

MOUNTING   AND  PRESERVING   OBJECTS   FOR   THE   MICROSCOPE. 

FOR  the  permanent  preservation  of  specimens,  various 
means  are  employed,  according  to  the  nature  of  the  object 
and  the  particular  line  of  investigation  desired.  Few,  if 
any,  objects  show  all  their  peculiarities  of  structure  or 
adaptation  to  function,  and  for  scientific  work  it  is  often 


MOUNTING    AND    PRESERVING    OBJECTS.  77 

necessary  to  have  the  same  structure  prepared  in  different 
ways. 

Opaque  Objects  have  sometimes  been  attached  by  thick 
gum  to  small  disks  of  paper,  etc.,  or  to  the  bottom  and 
sides  of  small  pill-boxes,  or  in  cavities  in  slides  of  bone  or 
wood,  but  they  are  better  preserved  on  glass  slides,  as 
hereafter  described. 

The  most  convenient  form  of  slide  for  microscopic  pur- 
poses is  made  of  flattened  crown  or  flint  glass,  cut  into 
slips  of  three  inches  by  one  inch,  and  ground  at  the  edges. 
Some  preparations  are  mounted  on  smaller  slips,  but  they 
are  less  convenient  than  the  above,  which  is  regarded  as 
the  standard  size. 

On  such  slides  objects  are  fixed,  and  covered  by  a  square 
or  round  piece  of  thin  glass,  varying  from  ^th  to  -g^th 
of  an  inch  in  thickness.  Both  slides  and  thin  glass  can 
be  procured  at  opticians'  stores.  Laminae  of  mica  or  talc 
are  sometimes  used  for  lack  of  better  material,  but  are  too 
soft.  For  object-glasses  of  the  shortest  focal  length,  how- 
ever, it  is  necessary  at  times  to  resort  to  this  sort  of  cov- 
ering. 

Great  care  should  be  taken  to  have  both  slide  and  cover 
clean.  With  thin  glass  this  is  difficult,  owing  to  its  brit- 
tleness.  Practice  will  teach  much,  but  for  the  thinnest 
glass  two  flat  pieces  of  wood  covered  with  chamois  leather, 
between  which  the  cover  may  lie  flat  as  it  is  rubbed,  will 
be  serviceable. 

Very  thin  specimens  may  be  mounted  in  balsam,  glyc- 
erin, etc.,  covered  with  the  thin  glass  cover,  and  then 
secured  by  a  careful  application  of  cement  to  the  edges  of 
the  cover.  If,  however,  the  pressure  of  the  thin  glass  be 
objectionable,  or  the  object  be  of  moderate  thickness,  some 
sort  of  cell  should  be  constructed  on  the  slide. 

The  thinnest  cells  are  made  with  cement,  as  gold  size, 
Brunswick  black,  etc.,  painted  on  with  a  camel's-hair  pen- 
cil. For  preparing  these  with  elegance,  Shadbolt's  turn- 


78 


THE    MICROSCOPIST. 


table  has  been  contrived  (Fig.  36).  The  slide  is  placed 
between  the  springs,  and  while  rotated,  a  ring  of  varnish 
of  suitable  breadth  is  made  on  the  glass. 

A  piece  of  thin  glass  (or  even  of  thick  glass)  may  be 
perforated  and  cemented  to  the  slide  with  marine  glue  by 


FIG.  36. 


Shadbolt's  Turntable  for  making  Cement-Cells. 

the  aid  of  heat;  or  vulcanite,  lead,  tin,  gutta  percha,  etc., 
may  be  made  into  a  cell  in  a  similar  way  as  seen  in  Fig. 
37. 

The  perforation  of  thin  glass  may  be  easily  performed 
by  cementing  it  over  a  hole  in  a  brass  plate,  etc.,  with 
marine  glue,  and  punching  it  through  with  the  end  of  a 

FIG.  37. 


Cell  of  Glass,  Vulcanite,  etc. 

file.  The  edges  may  then  be  filed  to  the  size  of  the  hole, 
and  the  glass  removed  by  heating  the  brass.  Thicker 
glass  may  be  bored  with  a  file  by  moistening  it  with 
turpentine. 

Dry  objects,  especially  if  they  are  transparent,  as  dia- 
toms, thin  sections  of  bone,  crystals,  etc.,  may  be  attached 
to  the  slide  with  Canada  balsam,  etc.,  covered  with  thin 


MOUNTING    AND    PRESERVING    OBJECTS.  '79 

glass,  which  should  be  cemented  at  the  edges,  and  gummed 
over  all  a  strip  of  colored  or  lithographed  paper,  in  which 
an  aperture  has  been  made  with  a  punch. 

Mounting  in  Balsam  or  Dammar  Varnish  is  suitable  for 
a  very  large  proportion  of  objects.  It  increases  the  trans- 
parency of  many  structures,  filling  up  interstices  and  cavi- 
ties, and  giving  them  a  smooth,  beautiful  appearance. 
Very  delicate  tissues,  as  fine  nerves,  etc.,  are  rendered  in- 
visible by  it,  and  require  other  fluids,  as  glycerin. 

Before  mounting  in  balsam,  the  object  should  be  thor- 
oughly dry,  otherwise  a  milky  appearance  will  result.  It 
should  then  be  placed  in  oil  of  cloves  or  of  turpentine  to 
remove  greasiuess  and  increase  the  transparency.  A  clean 
slide,  warmed  over  a  spirit-lamp  or  on  a  hot  plate,  should 
then  have  a  little  balsam  placed  on  its  centre,  and  the 
object  carefully  lifted  from  the  turpentine  is  put  into  the 
balsam  and  covered  with  another  drop.  The  slide  should 
then  be  gently  warmed,  and  any  air-bubbles  pricked  with 
a  needle-point  or  drawn  aside.  The  thin  glass  cover  should 
be  warmed  and  put  on  gently,  in  such  a  way  as  to  lean 
first  on  one  edge  and  fall  gradually  to  a  horizontal  posi- 
tion. The  slide  may  be  warmed  again,  and  the  superflu- 
ous balsam  pressed  from  under  the  cover  by  the  pressure 
of  a  clean  point  upon  it. 

If  the  object  is  full  of  large  air-spaces  and  is  not  likely 
to  be  injured  by  heat,  the  air  may  be  expelled  by  gently 
boiling  it  in  the  balsam  on  the  slide.  If  the  object  be  one 
which  will  curl  up,  or  is  otherwise  injured  by  heat,  the 
air-pump  must  be  resorted  to.  A  cheap  substitute  for  the 
air-pump  may  be  made  by  fitting  a  piston  into  a  tolerably 
wide  glass  tube  closed  at  one  end.  The  piston  should 
have  a  valve  opening  outwards.  The  preparation  in  bal- 
sam may  be  placed  at  the  bottom  of  the  tube,  and  a  few 
strokes  of  the  piston  will  exhaust  the  air. 

To  fill  a  deep  cell  with  Canada  balsam,  it  may  be  well 
to  fill  it  first  with  turpentine  and  place  the  specimen  in 


80*  THE    MICROSCOPIST. 

it.  Then  pour  in  the  balsam  at  one  end,  the  slide  being 
inclined  so  that  the  turpentine  may  run  out  at  the  other. 
Lay  the  cover  on  one  edge  of  the  cell  and  gradually  lower 
it  till  it  lies  flat.  In  this  way  air  may  be  excluded. 

The  solution  of  balsam  in  chloroform  needs  no  heat, 
and  has  little  liability  of  air-bubbles. 

The  excess  of  balsam  round  the  edge  of  the  glass  cover 
may  be  removed  with  a  knife  and  cleaned  with  turpentine 
or  benzine,  etc. 

For  animal  tissues,  the  oil  of  cloves  is  sometimes  used 
instead  of  turpentine  to  increase  the  transparency,  and  a 
wet  preparation,  as  a  stained  or  injected  specimen,  may 
be  mounted  in  balsam  or  Dammar  by  lirst  placing  it  in 
absolute  alcohol  to  extract  the  water,  then  transferring 
to  oil  of  cloves  or  turpentine,  and  lastly,  to  the  balsam. 
In  a  reverse  order,  a  specimen  from  balsam  may  be  cleaned 
and  mounted  in  fluid. 

Mounting  in  Fluid  is  necessary  for  the  preservation  of 
the  most  delicate  tissues  and  such  as  may  be  injured  by 

FIG.  38. 


Spring  Clip. 

drying.  Glycerin  is  perhaps  the  most  generally  useful 
fluid.  (See  Preservative  Fluids,  page  73.) 

For  mounting  in  fluid,  it  is  safer  to  have  a  thin  cell  of 
varnish  prepared  first  than  to  risk  the  running  in  of  the 
cement  under  the  cover,  as  will  be  likely  to  occur  other- 
wise. 

The  air-pump  is  sometimes  needed  in  mounting  in  fluid 
to  get  rid  of  air-bubbles.  A  spring  clip  (Fig.  38)  is  also 


MOUNTING    AND    PRESERVING    OBJECTS.  81 

a  useful  instrument  for  making  moderate  pressure  on  the 
glass  cover  until  the  cement  on  its  edge  is  dry.  A  drop- 
ping-tube  with  a  bulbous  funnel,  covered  with  thin  india- 
rubber,  for  taking  up  and  dropping  small  quantities  of 
fluid,  wrill  also  be  of  service. 

Superfluous  fluid  may  be  removed  from  the  edge  of  the 
cover  by  a  piece  of  blotting-paper,  care  being  used  not  to 
draw  away  the  fluid  beneath  the  cover. 

As  soon  as  objects  are  mounted,  the  slides  should  be 
labelled  before  cementing  is  finished,  otherwise  time  will 
be  lost  in  searching  for  a  particular  object  among  others, 
or  the  name  may  be  forgotten. 

Boxes  of  wood  or  of  pasteboard,  with  grooved  racks  at 
the  sides,  are  occasionally  used  for  preserving  a  collection 
of  specimens.  It  is  better,  however,  to  have  a  cabinet 
with  drawers  or  trays  so  that  the  specimens  may  lie  flat, 
with  their  ends  towards  the  front  of  the  drawer.  A  piece 
of  porcelain  on  the  end  of  the  drawer  is  convenient  for 
the  name  of  the  class  of  objects  contained,  to  be  written 
on  with  lead-pencil. 

Collecting  Objects. — The  methods  pursued  by  naturalists 
generally  will  suffice  for  a  large  proportion  of  the  objects 
which  are  matters  of  microscopic  inquiry,  but  "there  are 
others  which,  from  their  minuteness,  require  special  search. 
Many  fresh-water  species  of  microscopic  organisms  inhabit 
pools,  ditches,  and  streams.  Some  attach  themselves  to 
the  stems  and  leaves  of  aquatic  plants,  or  to  floating  and 
decaying  sticks,  etc.  Others  live  in  the  muddy  sediment 
at  the  bottom  of  the  water.  A  pond  stick  has  been  con- 
trived for  the  collection  of  such  organisms,  consisting  of 
two  lengths,  sliding  one  within  the  other,  so  that  it  may 
be  used  as  a  walking-cane.  In  a  screw  socket  at  one  end 
may  be  placed  a  curved  knife  for  cutting  portions  of  plants 
which  contain  microscopic  parasites;  or  a  screw  collar  for 
carrying  a  screw-topped  bottle,  which  serves  to  bring  up 
a  sample  of  liquid ;  or  it  may  have  a  ring  for  a  muslin  net. 

6 


82  THE    MICROSCOPIST. 

The  net  should  be  confined  by  an  india-rubber  band  in  a 
groove,  so  as  to  be  slipped  off  readily  and  emptied  into  a 
bottle.  The  collector  should  have  enough  bottles  to  keep 
organisms  from  each  locality  separate,  and  when  animal- 
cules are  secured  enough,  air  should  be  left  to  insure  their 
safety. 

Marine  organisms  may  be  obtained  in  a  similar  way  if 
they  inhabit  the  neighborhood  of  the  shore,  but  others 
can  only  be  secured  by  means  of  the  dredge  or  tow-net. 
The  latter  may  be  of  fine  muslin  sewn  to  a  wire  ring  of 
twelve  inches  diameter.  It  may  be  fastened  with  strings 
to  the  stern  of  a  boat,  or  held  by  a  stick  so  as  to  project 
from  the  side.  For  the  more  delicate  organisms,  the  boat 
should  be  rowed  slowly,  so  that  the  net  may  move  gently 
through  the  water.  Firmer  structures  may  be  obtained 
by  attaching  a  wide-mouthed  bottle  to  the  end  of  a  net 
made  conical,  and  double,  so  that  the  inner  cone  may  act 
as  a  valve.  The  bottle  may  be  kept  from  sinking  by  a 
piece  of  cork.  Such  a  net  may  be  fixed  to  the  stern  of  a 
vessel,  and  drawn  up  from  time  to  time  for  examination. 

Minute  organisms  may  be  examined  on  the  spot  by 
fishing  them  out  of  the  bottle  with  a  pipette,  or  small 
glass  tube,  and  placing  them  on  a  slide.  A  Goddington 
or  other  pocket  lens  will  suffice  to  show  which  are  desir- 
able for  preservation. 

Many  of  the  lower  animals  and  plants  may  be  kept 
alive  in  glass  jars  for  some  time.  Frogs,  etc.,  may  be 
kept  under  wire  covers  with  a  large  piece  of  moist  sponge. 

Aquaria  of  various  sorts  may  be  procured  and  stocked 
at  small  expense,  and  will  afford  a  constant  source  of  in- 
struction. For  fresh- water  aquaria  the  bottom  of  the  jar, 
etc  ,  should  be  covered  with  rich  black  earth,  made  into 
a  paste,  and  this  should  be  surmounted  with  a  layer  of 
fine  washed  sand.  Roots  of  Valisneria,  Anacharis,  or 
Char  a  may  then  be  planted  in  the  earth  and  the  vessel 
filled  with  water.  As  soon  as  the  water  is  clear,  put  a 


MOUNTING    AND    PRESERVING    OBJECTS.  83 

few  fresh-water  molluscs  in  to  keep  clown  the  growth  of 
confervse,  especially  such  as  feed  on  decayed  vegetable1 
matter,  as  Planorbis  carinatus,  Paludina  vivipara,  or  Am- 
phibia glutinosa.  When  bubbles  of  oxygen  gas  <appearr 
fish,  water  insects,  etc.,  may  be  introduced. 

Marine  aquaria  require  more  skill  than  those  for  fresfo 
water,  but  for  temporary  purposes,  the  plan  described  by 
Mr.  Highley,  in  Dr.  Beale's  How  to  Work  with  the  Micro- 
scope, is  excellent.  He  fills  a  number  of  German  beaker 
glasses  with  fresh  sea-water,  and  places  them  in  a  sunny 
window.  He  then  drops  in  each  one  or  two  limpet  shells 
from  which  the  animals  have  been  removed,  and  upon 
which  small  plants  of  Enteromorpha  and  Ulva  are  growing. 
In  a  short  time  the  sides  of  the  jars  next  the  light  become 
coated  with  spores.  He  keeps  the  other  sides  clean  with 
a  piece  of  wood  or  sponge,  so  as  to  observe  the  small 
marine  animals  which  may  now  be  placed  in  the  beakers. 
In  this  way  a  collection  will  keep  healthy  for  months. 
After  the  sides  are  covered  with  spores,  the  sea-weeds 
may  be  removed,  and  the  jars  placed  on  a  table  at  such  a 
distance  from  the  window  that  the  light  impinges  only 
on  the  coated  half,  taking  care  that  there  is  sufficient  light 
to  stimulate  the  spores  to  throw  off  bubbles  of  oxygen 
daily. 

Prawns,  fish,  actiniae,  etc.,  may  be  fed  on  shreds  of  beef 
which  has  been  pounded  and  dried,  and  then  macerated 
in  sea-water  for  a  few  minutes.  All  dead  animals,  slime, 
or  effete  matter  should  be  removed  by  wooden  forceps, 
etc.,  as  soon  as  noticed. 


• 

J  N  I y  a  R  8  I T  Y   O  F 


84:  THE    MICROSCOPIST. 

CHAPTER   VII. 

THE   MICROSCOPE   IN   MINERALOGY    AND   GEOLOGY. 

MICROSCOPIC  examination  of  minute  fossil  organisms,  as 
Diatoms,  Foraminifera,  spicules  of  sponge,  etc.,  has  long 
been  a  subject  of  interest.  Latterly,  however,  the  micro- 
scope has  been  found  to  be  essential  to  the  study  of  phys- 
ical geology  and  petrology.  How  many  crude  and  verbose 
theories  respecting  cosmogony  will  disappear  by  this  means 
of  investigation  time  must  reveal,  but  the  animal  nature 
of  the  Eozoon  Canadense  found  in  the  Serpentine  Lime- 
stone of  the  Lauren tian  formation  of  Canada,  parallel  with 
tfre  Fundamental  Gneiss  of  Europe,  and  the  discovery  by 
Mr.  Sorby*  of  minute  cavities  filled  with  fluid  in  quartz 
and  volcanic  rocks,  are  indications  that  speculations  based 
upon  a  merely  external  or  even  chemical  examination  of 
rock  structures  are  immature  and  inadequate. 

The  systematic  study  of  microscopic  mineralogy  and 
geology  will  require  a  large  outlay  of  time  and  patience, 
and  the  field  is  one  which  is  scarcely  trodden.  The  plan 
of  this  work  will  only  permit  a  brief  outline,  sufficient  to 
aid  a  beginner,  and  indicating  the  value  and  the  methods 
of  minute  investigation. 

Preparation  of  Specimens. — Examination  of  the  outer  i 
surface  of  a  mineral  specimen,  viewed  as  an  opaque  body 
with  a  low  power  and  by  condensed  light,  is  sometimes 
useful.  The  metals  and  their  alloys,  with  most  of  their 
combinations  with  sulphur,  etc  ,  admit  of  no  other  method. 
Occasionally,  as  in  iron  and  steel,  the  microscopic  structure 
is  best  seen  by  polishing  the  surface,  and  then  allowing 
the  action  of  very  dilute  nitric  acid.  Mr.  Forbesf  states 

*  See  Beale's  How  to  Work  with  the  Microscope. 

f  The  Microscope  in  Geology,  Popular  Science  Review,  No.  25.. 


THE    MICROSCOPE    IN    MINERALOGY    AND    GEOLOGY.      85 

that  many  vitreous  specimens  (quite  transparent)  show  no- 
trace  of  structure  until  the  surface  has  been  carefully  acted 
on  by  hydrofluoric  acid. 

It  is  generally  necessary  to  have  the  specimens  flat  and 
smooth,  and  thin  enough  to  transmit  light.  Sometimes 
fragments  may  be  thin  enough  to  show  structure  when 
mounted  in  balsam,  as  in  the  case  of  quartz,  obsidian,  pitch- 
stone,  etc.,  but  usually  thin  sections  must  be  ground  and 
polished. 

Chip  off  a  fragment  of  the  rock  as  flat  and  thin  as  pos- 
sible, or  cut  with  a  lapidary's  wheel,  or  a  toothless  saw  of 
sheet-iron  with  emery.  Grind  down  the  specimen  on  an 
iron  or  pewter  plate  in  a  lathe  until  perfectly  flat.  Then 
grind  with  finer  emery  on  a  slab  of  fine-grained  marble  or 
slate,  and  finish  with  water  on  a  fine  hone,  avoiding  all 
polishing  powders  or  oil.  When  perfectly  smooth,  cement 
the  specimen  on  a  square  of  glass  with  Canada  balsam, 
and  grind  the  other  side  until  as  thin  as  necessary,  finish 
as  before,  remove  it  from  the  glass,  and  mount  on  a  glass 
slide  in  balsam. 

In  this  way,  most  silicates,  chlorides,  fluorides,  carbo- 
nates, sulphates,  borates,  many  oxides,  sulphides,  etc.,  may 
be  prepared  for  examination  by  transmitted  light.  Very 
soft  rocks  may  be  soaked  in  turpentine,  then  in  soft  balsam, 
and  afterwards  heated  until  quite  hard.  The  deep  scratches 
on  hard  minerals,  like  quartz,  left  by  the  use  of  coarse 
emery,  may^  be  removed  by  using  fine  emery  paper  held 
flat  on  a  piece  of  plate  glass,  and  finally  polished  with 
rouge  on  parchment.  Perhaps  oxide  of  chromium  from 
its  hardness  will  be  found  the  best  polishing  material. 
Crystals  of  soluble  salts  may  be  ground  on  emery  paper 
and  polished  with  rouge.  Sometimes  much  may  be  learned 
by  acting  on  one  side  only  of  a  specimen  with  dilute  acid. 

Examination  of  Specimens. — The  object  of  microscopic 
examination  of  minerals  is  to  determine  not  only  the  nature 
of  the  material  of  which  they  are  composed,  but  also,  and 


86  THE    MICROSCOPIST. 

chiefly,  their  structure,  whether  homogeneous,  derived 
from  the  debris  of  previous  rocks,  or  from  the  agency  of  the 
organic  world.  Ordinary  mineralogical  characteristics,  as 
to  hardness,  specific  gravity,  color,  lustre,  form,  cleavage, 
and  fusibility,  and  above  all,  chemical  composition,  may 
suffice  to  show  the  material,  but  the  microscope  will  give 
valuable  assistance  to  this  end,  and  is  essential  to  a  knowl- 
edge of  structure. 

Crystalline  Forms. — The  laws  of  crystallography  teach 
that  each  chemical  combination  corresponds  to  a  distinct 
relation  of  all  the  angles  which  can  possibly  arise  from 
the  primary  form,  so  that  the  angular  inclination  of  the 
facets  of  a  crystal  is  a  question  of  importance.  This  can 
be  ascertained  by  a  microscope  having  a  revolving  stage, 
properly  graduated,  or  by  the  use  of  a  goniometer,  which 
is  a  thread  stretched  across  the  focus  of  the  eye-lens,  and 
attached  to  a  movable  graduated  circle  and  vernier.  The 
eye-piece  attached  to  the  polariscope  of  Hartnack  is  thus 
arranged,  so  as  to  act  also  as  a  goniometer. 

Crystals  are  assumed  to  possess  certain  axes,  and  the 
form  is  determined  by  the  relation  of  the  plane  surface  to 
these  axes.  Although  the  forms  of  crystals  are  almost 
infinitely  varied,  they  may  be  classified  into  seven  crystal- 
lographic  systems. 

1.  The  Regular  Cubic  or  Monom.etric  System  (Fig.  39). — 
These  crystals  are  symmetrical,  about  three  rectangular 
axes.     The  simplest  forms  are  the  cube  and  octahedron. 
Examples,  diamond,  most  metals,  chloride  of  sodium,  fluor 
spar,  alum. 

2.  The  Quadratic  or  Dimetric  System  (Fig.  40). — Crystals 
symmetrical,  about  three  rectangular  axes,  but  only  two 
axes  of  equal  length.     Examples,  sulphate  of  nickel,  tung- 
state  of  lead,  and  double  chloride  of  potassium  and  cop- 
per. 

3.  Hexagonal  or  Rhombohedral  System  (Fig.  41). — Crys- 
tals with  four  axes ;  three  equal  in  length,  in  one  plane, 


FIG.  39. 


Principal  or  Vertical  Axes.  Secondary  or  Lateral  Axes. 

FIG.  41. 


Principal  Axes.  Secondary  Axes. 

'  FIG.  42. 


Principal  Axes.  Secondary  Axes. 

FIG.  44. 


Principal  Axes. 


Secondary  Axes. 


88  THE    MICROSCOPIST. 

and  inclined  60°  to  each  other,  and  a  principal  axis  at 
right  angles  to  the  plane  of  the  others.  Examples,  quartz, 
beryl,  and  calc-spar. 

4.  Rhombic  or  Trimetric  System  (Fig.  42). — Three  rec- 
tangular axes,  all  of  different  lengths.    Examples,  sulphate 
of  potassium,  nitrate  of  potassium,  sulphate  of  barium, 
and  sulphate  of  magnesium. 

5.  Oblique  Prismatic  or  Monoclinic  (Fig.  43). — Two  axes 
obliquely  inclined,  and  a  third  at  right  angles  to  the  plane 
of  these  two ;  all  three  being  unequal.     Examples,  ferrous 
sulphate,  sugar,  gypsum,  and  tartaric  acid. 

6.  Didinic  System. — Two  axes  at  right  angles,  and  a 
third  oblique  to  the  plane  of  these ;    the  primary  form 
being  a  symmetrical  eight  sided  pyramid. 

7.  Doubly  Oblique  Prismatic  or  Tridinic  (Fig.  44). — Three 
axes  all  inclined  obliquely  and  of  equal  length.     Example, 
sulphate  of  copper. 

Crystalline  structure  being  inherent  in  the  nature  of 
the  mineral,  becomes  perceptible  by  the  manner  of  divi- 
sion. A  slight  blow  on  a  piece  of  calc-spar  will  separate 
it  into  small  rhombohedrons  or  parallelopipeds,  or  produce 
internal  fissures  along  the  planes  of  cleavage,  which  will 
suffice  to  determine  their  angles. 

Crystals  are  often  found  in  groups,  with  various  modes 
of  arrangement.  Cubes  are  sometimes  aggregated  so  as 
to  form  octahedra,  and  prismatic  crystals  are  often  united 
together  at  one  extremity.  But  the  most  singular  groups 
are  those  called  hemi tropes,  because  they  resemble  a  crys- 
tal cut  in  two,  with  one  part  turned  half  round  and  re- 
united to  the  other. 

In  all  the  numerous  forms,  however,  we  find  in  the  same 
species  the  same  angles  or  inclination  of  planes,  although 
the  unequal  size  of  the  faces  may  lead  to  great  apparent 
irregularity,  as  in  distorted  crystals  of  quartz,  where  one 
face  of  the  pyramid  is  enlarged  at  the  expense  of  the  rest. 


THE    MICROSCOPE    IN    MINERALOGY    AND    GEOLOGY.      89 

An  apparent  distortion  may  also  be  produced  by  an  oblique 
section. 

The  following  examples  may  be  of  service,  as  showing 
the  value  of  angular  measurement  in  minerals: 

Quartz.  Rhombohedral  system.  Inclination  of  two 
adjoining  faces  94°  15'. 

Felspar.     Monoclinic.     Cleavage  planes  at  right  angles. 

Albite  or  soda  felspar.     Triclinic.     Angle  93°  36'. 

Mica.     Oblique  prisms. 

Magnesian  mica.    Right,  rhombic,  or  hexagonal  prisms. 

Garnet.     Dodecahedrons  or  trapezohedrons. 

Idocrase.     Square  prisms. 

Epidote.     Oblique  prisms. 

Scapolite.     Square  and  octagonal  prisms. 

Andalusite.     Prisms  of  90°  44'. 

Staurotide.     Rhombic  prisms  of  129°  20'. 

Tourmaline.     Three,  six,  nine,  or  twelve-sided  prismsl  ' 

Topaz.     Rhombic  prisms  of  124°  19'. 

Beryl.     Six-sided  prisms. 

Hornblende.     Monoclinic.     124°  30'. 

Augite  or  pyroxene.     Monoclinic.     87°  5'. 

Calcite  or  carbonate  of  lime.  Forms  various,  but  105° 
5'  between  the  cleavage  faces. 

Magnesite.     Angle  107°  29'. 

Dolomite.     106°  15'. 

Gypsum.     Monoclinic. 

Crystals  within  Crystals. — Many  specimens  which  appear 
perfectly  homogeneous  to  the  naked  eye  are  shown  by  the 
microscope  to  be  very  complex.  The  minerals  of  erupted 
lavas  are  often  full  of  minute  crystals,  leading  to  very 
anomalous  results  of  chemical  analysis.  Some  care  is 
needed  at  times  to  distinguish  such  included  minerals 
from  cavities  filled  with  fluid.  The  use  of  polarized  light 
will  sometimes  determine  this  point. 

Cavities  in  Crystals. — Mr.  Sorby  has  shown  that  the 
various  cavities  in  minerals  containing  air,  water,  glass, 


90  THE    MICROSCOPIST. 

• 

or  stone  will  often  indicate  under  what  conditions  the 
rock  was  formed.  Thus  cr3Tstals  with  water  cavities  were 
formed  from  solution  ;  those  with  stone  or  glass  cavities 
from  igneous  fusion ;  those  with  both  kinds  by  the  com- 
bined influence  of  highly  heated  water  .and  melted  rock 
under  great  pressure;  while  those  that  contain  no  cavi- 
ties were  formed  very  slowly,  or  from  the  fusion  of  homo- 
geneous substance. 

Use  of  Polarized  Light. — Mr.  Sorby  states  that  the 
action  of  crystals  on  polarized  light  is  due  to  their  double 
refraction,  which  depolarizes  the  polarized  beam,  and 
gives  rise  to  colors  by  interference  if  the  crystal  be  not 
too  thick  in  proportion  to  the  intensity  of  its  power  of 
double  refraction.  This  varies  much,  according  to  the 
position  in  which  the  crystal  is  cut,  yet  we  may  form  a 
general  opinion,  since  it  is  the  intensity  and  not  the  char- 
acter of  the  depolarized  light  which  varies  according  to 
the  position  of  the  crystal.  There  are  two  axes  at  right 
angles  to  each  other,  and  when  either  of  them  is  parallel 
to  the  plane  of  polarization,  the  crystal  has  no  depolariz- 
ing action,  and  if  the  polarizing  and  analyzing  prisms  are 
crossed,  it  looks  black.  On  rotating  the  crystal  or  the 
plane  of  polarization,  the  intensity  of  depolarizing  action 
increases  until  the  axes  are  at  45°,  and  then  diminishes 
till  the  other  axis  is  in  the  plane.  If,  therefore,  this  takes 
place  uniformly  over  a  specimen,  we  know  that  it  has  one 
simple  crystalline  structure,  but  if  it  breaks  up  into  de- 
tached parts,  we  know  it  is  made  up  of  a  number  of  sepa- 
rate crystalline  portions. 

The  definite  order  that  may  occur  in  the  arrangement 
of  a  number  of  crystals  may  indicate  important  differences. 
Some  round  bodies,  for  example,  like  oolitic  grains,  have 
been  formed  by  crystals  radiating  from  a  common  nu- 
cleus ;  whilst  others,  as  in  meteorites,  have  the  structure 
of  round  bodies  which  crystallized  afterwards. 

Sir  D.  Brewster  discovered  that  many  crystals  have 


THE    MICROSCOPE    IN    MINERALOGY    AND    GEOLOGY.       91 

two  axes  of  double  refraction,  or  rather  axes  around  which 
double  refraction  occurs.  Thus  nitre  crystallizes  in  six- 
sided  prisms,  with  angles  of  about  120°.  It  has  two  axes 
of  double  refraction  inclined  about  2J°  to  the  axes  of  the 
prism,  and  5°  to  each  other,  so  that  a  piece  cut  from  such 
a  crystal  perpendicular  to  the  axes,  shows  a  double  system 
of  rings  when  a  ray  of  polarized  light  is  transmitted. 
When  the  line  connecting  the  axes  is  inclined  45°  to  the 
plane  of  polarization,  a  cross  is  seen,  which  gradually 
assumes  the  form  of  two  hyperbolic  curves  on  rotating 
the  specimen.  If  the  analyzer  be  revolved,  the  black  cross 
will  be  replaced  by  white,  the  red  rings  by  green,  the  yel- 
low by  indigo,  etc.  These  rings  have  the  same  colors  as 
thin  plates,  or  a  system  of  rings  round  one  axis.  Mica 
has  tw,o  sets  of  rings,  with  the  angle  between  the  axes  of 
60°  to  75°.  Magnesian  mica  gives  an  angle  of  5°  to  20°. 
Determination  of  the  Origin  of  Rock  Specimens. — Mr. 
Forbes  has  shown  that  the  primary  or  eruptive  rocks, 
consisting  chiefly  of  crystallized  silicates,  with  small 
quantities  of  other  minerals,  are  developed  as  more  or 
less  perfect  crystals  at  all  angles  to  one  another,  indicat- 
ing the  fluid  state  of  the  mass  at  some  previous  time. 
The  secondary  or  sedimentary  rocks  consist  of  rocks 
formed  by  the  immediate  products  of  the  breaking  up  of 
eruptive  rocks,  or  are  built  of  the  debris  of  previous  erup- 
tive or  sedimentary  rocks,  or  composed  of  extracts  from 
aqueous  solution  by  crystallization,  precipitation,  or  the 
action  of  organic  life.  The  accompanying  figures,  selected 
from  Mr.  Forbes's  article  in  the  Popular  Science  Review, 
well  illustrate  this  method  of  investigation.  Plate  II, 
Fig.  45,  is  a  section  of  lava  from  Vesuvius,  magnified 
twelve  diameters,  showing  crystals  of  augite  in  a  hard 
gray  rock.  Plate  II,  Fig.  46,  is  a  volcanic  rock  from 
Tahiti,  consisting  of  felspar,  with  olivine  and  magnetic 
oxide  of  iron,  and  numerous  crystals  of  a  pyroxenic  min- 
eral. Plate  II,  Fig.  47,  is  pitchstone  from  a  dyke  in  new 


92  '  THE    MICROSCOPIST. 

red  sandstone,  magnified  seventy-five  diameters.  Exter- 
nally it  resembles  dirty  green  bottle-glass,  but  shows  in 
the  microscope  an  arborescent  crystallization  of  a  green 
pyroxenic  mineral  in  a  colorless  felspar  base.  Plate  II, 
Fig.  48,  shows  auriferous  diorite  from  Chili,  consisting  of 
felspar,  with  hornblende  and  crystals  of  iron  pyrites,  mag- 
nified thirty  diameters.  Plate  II,  Fig.  49,  is  a  section  of 
granite  from  Cornwall,  with  crystals  of  orthoclase,  hexag- 
onal crystals  of  brown  mica,  and  colorless  quartz,  which 
a  higher  power  shows  to  contain  fluid  cavities,  magnified 
twenty-five  diameters.  Plate  II,  Fig.  50,  a  volcanic  rock 
from  Peru,  composed  of  felspar,  dark  crystals  of  augite, 
hexagonal  crystals  of  dark  mica,  and  a  little  magnetic 
oxide  of  iron,  magnified  six  diameters.  Plate  II,  Fig. 
51,  lower  silurian  roofing-slate,  cut  at  right  augles^to  the 
cleavage,  showing  that  the  latter  is  not  due  to  crystalline 
but  to  mechanical  arrangement,  magnified  two  hundred 
diameters.  Plate  II,  Fig.  52,  is  an  oolitic  specimen  from 
Peru,  regarded  as  an  eruptive  rock  by  D'Orbigny,  but 
shown  in  the  microscope  to  be  a  mere  aggregation  of 
sand,  etc.,  without  the  crystalline  character  of  eruptive 
rocks. 

Materials  of  Organic  Origin. — Rocks  and  strata  derived 
from  plants  or  animals  may  be  arranged  in  four  groups : 
1.  The  calcareous,  or  those  of  which  limestones  have  been 
formed,  as  corals,  corallines,  shells,  crinoids,  etc.  2.  The 
siliceous,  which  have  contributed  to  the  silica,  and  may 
have  originated  flints,  as  the  microscopic  shields  of  dia- 
toms and  siliceous  spiculee  of  sponges.  3.  The  phosphatic, 
as  bones,  excrement,  etc.  Fossil  excrements  are  called 
coprolites,  and  those  of  birds  in  large  accumulations, 
guano.  4.  The  carbonaceous,  or  those  which  have  afforded 
coal  and  resin,  as  plants. 

To  examine  the  structure  of  coal,  it  is  necessary  to  have 
very  thin  sections.  From  its  friability,  this  is  a  process 
of  great  difficulty.  The  Micrographic  Dictionary  recom- 


THE    MICROSCOPE    IN    MINERALOGY    AND    GEOLOGY.      93 

mends  the  maceration  of  the  coal  for  about  a  week  in  a 
solution  of  carbonate  of  potassium,  when  thin  slices  may 
be  cut  with  a  razor.  These  should  be  gently  heated  in 
nitric  acid,  and  when  they  turn  yellow,  washed  in  cold 
water  and  mounted  in  glycerin,  as  spirit  and  balsam  ren- 
der them  opaque.  Sometimes,  as  in  anthracite,  casts  of 
vegetable  fibres  may  be  obtained  in  the  ash  after  burning 
and  mounted  in  balsam. 

The  lignites  of  the  tertiary  period  show  a  vegetable 
structure  similar  to  the  woods  of  the  present  period,  but 
the  older  coal  of  the  palaeozoic  series  is  a  mass  of  decom- 
posed vegetable  matter  chiefly  derived  from  the  decay  of 
coniferous  wood,  analogous  to  the  araucariae,  as  is  seen 
from  the  peculiar  arrangement  of  the  glandular  dots  on 
the  woody  fibres.  Traces  of  ferns,  sigillarise,  calarnites, 
etc.,  such  as  are  preserved  in  the  shales  and  sandstones  of 
the  coal  period,  are  also  met  with,  but  their  structure  has 
not  been  preserved. 

Professor  Heer,  of  Zurich,  has  described  and  classified 
several  hundred  species  of  fossil  plants  from  the  miocene 
beds  of  Switzerland  by  the  outlines,  nervation,  and  micro- 
scopic structure  of  the  leaves  and  character  of  sections  of 
the  wood.  Several  hundred  kinds  of  insects  "aiso  have 
been  found  in  the  same  strata.  It  is  remarkable  that  a 
great  part  of  this  fossil  flora  is  such  as  is  now  common 
to  America,  as  evergreen  •  oaks,  maples,  poplars,  ternate- 
leaved  pines,  and  the  representatives  of  the  gigantic 
sequoias  of  California. 

The  researches  of  palaeontologists  have  brought  to  light 
nearly  two  thousand  species  of  fossil  plants,  of  which 
about  one-half  belong  to  the  carboniferous  and  one-fourth 
to  the  tertiary  formations. 

The  rapid  multiplication  of  the  minute  microscopic 
organisms  called  diatoms,  is  such  that  Professor  Ehren- 
berg  affirms  it  to  have  an  important  influence  in  blocking 
up  harbors  and  diminishing  the  depth  of  channels.  These 


94  THE    MICROSCOPIST. 

organisms,  now  generally  regarded  as  plants,  are  exceed- 
ingly small,  and  are  usually  covered  by  loricee  or  shields 
of  pure  silica,  beautifully  marked,  as  if  engraved.  These 
loricae  or  shells  having  accumulated  in  great  quantities, 
have  given  rise  to  very  extensive  siliceous  strata.  Thus 
the  " infusorial  earth"  of  Virginia,  on  which  Eichmond 
and  Petersburg  are  built,  is  such  a  deposit  eighteen  feet 
in  thickness.  The  polishing  material  called  Tripoli,  and 

FIG.  53. 


Fossil  Diatomacese,  etc.,  from  Mourne  Mountain,  Ireland:  a,  a,  a,  Gaillomlla  (Melo- 
seira)  procera,  and  G.  granulata;  it,  d,  d,  G.  biseriata  (side  view);  ft,  b,  Surirella  plicata; 
c,  S,  craticula;  k,  S,  ealedonic-a;  e,  Gomphonema  gracile;  /,  Cocconema  fusidium;  g, 
Tabellaria  vulgaris;  A,  1'innularia  dactylus;  i,  P.  nobilis;  /,  Synedra  ulna.  (From 
Carpenter.) 

the  deposit  called  in  Sweden  and  Norway  berg-mehl  or 
mountain  flour,  because  used  in  times  of  scarcity  to  mix 
with  flour  for  bread,  are  similarly  composed.  Strata  of 
white  rock  in  the  anthracite  region  of  Pennsylvania,  and 
from  the  sides  of  the  Sierra  Nevada  and  Cascade  ranges 
in  California  and  Oregon,  have  also  been  found  to  consist 
of  such  remains  (Fig.  53). 


THE    MICROSCOPE    IN    MINERALOGY    AND    GEOLOGY.      95 

The  lowest  type  of  animal  life,  consisting  of  minute 
portions  of  sarcode  or  animal  jelly,  having  the  power  of 
putting  forth  prolongations  of  the  body  at  will,  contain 
some  forms  which  cover  themselves  with  shells,  usually 
many-chambered,  of  carbonate  of  lime.  From  the  pores 
in  these  shells,  through  which  the  root-like  processes  of 
sarcode  are  protruded,  they  are  called  Foraminifera. 


FIG.  54. 


Fossil  Polycystina,  etc.,  from  Barbadoes:  a,  Podocyrtis  mitra;  6,  Rhabdolithus  scep- 
trum  ;  c,  Lychnocanium  falciferum;  d,  Encyrtidium  tubulus;  e,  Flustrella  conceiitrica; 
/,  Lychnocanium  lucerna;  g,  Encyrtidium  elegans;  h,  Dictyospyris  clathrus;  i,  Encyr- 
tidium mongolfieri;  k,  Stephanolithis  spinescens;  /,  S,  nodosa;  m,  Lithocyclia  ocellus; 
n,  Cephalolithis  sylvina;  o,  Podocyrtis  cothurnata;  p,  Ehabdolithes  pipa.  (From  Car- 
penter.) 

Another  class,  the  Polycystina,  secrete  a  siliceous  shell, 
usually  of  one  chamber.  The  accumulations  of  the  Fo- 
raminifera have  formed  our  chalk  beds,  while  the  Polycys- 
tina have  contributed  to  siliceous  strata,  like  the  Diato- 
macece  (Fig.  54). 

The  origin  of  white  chalk  strata  has  been  illustrated 


96  THE    MICROSCOPIST. 

by  the  deep-sea  soundings  made  preparatory  to  laying 
the  telegraph  cable  across  the  Atlantic  Ocean.  Professor 
Huxley  found  the  mud  composing  the  floor  of  the  ocean 
to  consist  of  minute  Rhizopods  or  Foraminifera,  of  the 
genus  Globigerina,  together  with  Polycystina  and  Dia- 
toms, and  a  few  siliceous  spiculse  of  sponges.  These  were 
connected  by  a  mass  of  living  gelatinous  matter,  to  which 
he  has  given  the  name  of  Bathybius,  and  which  contains 
minute  bodies  termed  Coccoliths  and  Coccospheres,  which 
have  also  been  detected  in  fossil  chalk.  It  is  said  that 
95  per  cent,  of  the  mud  of  the  North  Atlantic  consists  of 
Globigerina  shells. 

To  examine  Foraminifera  in  chalk,  rub  a  quantity  to 
powder  in  water  with  a  soft  brush,  and  let  it  settle  for  a 
variable  time.  The  first  deposits  will  contain  the  larger 
specimens,  with  fragments  of  shell,  etc. ;  the  smaller  fall 
next,  while  the  amorphous  particles  suspended  in  the 
water  may  be  cast  aside.  After  drying  such  specimens 
as  may  be  selected  by  the  use  of  a  dissecting  microscope 
or  Coddington  lens,  etc.,  they  may  be  mounted  in  balsam. 

The  flint  found  in  chalk  often  contains  Xanthidia, 
which  are  the  sporangia  of  Desmidiacese,  as  well  as  speci- 
mens of  sponge,  Foraminiferal  shells,  etc.  They  must  be 
cut  as  other  hard  minerals. 

There  are  other  deposits  besides  chalk  which  are  seen 
by  the  microscope  to  consist  of  minute  shells,  corals, 
etc.  A  section  of  oolitic  stone  will  often  show  that  each 
rounded  concretion  is  composed  of  a  series  of  concentric 
spheres  inclosing  a  central  nucleus  which  may  be  a  forami- 
niferal  shell.  The  green  sand  formation  is  composed  of 
the  casts  of  the  interior  of  minute  shells  which  have  them- 
selves entirely  disappeared.  The  material  of  these  casts, 
chiefly  silex  colored  with  iron,  has  not  only  filled  the  cham- 
bers of  the  shells,  but  has  penetrated  the  canals  of  the 
intermediate  skeleton. 

The  more  recent  discovery  by  Drs.  Dawson  and  Carpen- 


THE    MICROSCOPE    IN    MINERALOGY    AND    GEOLOGY.      97 

ter  of  the  organic  nature  of  those  serpentine  limestones 
in  the  Laurentian  formations  of  Canada  and  elsewhere, 
which  are  products  of  the  growth  of  the  gigantic  forami- 
niferal  Eozoon  Canadense,  over  immense  areas  of  the 
ancient  sea-bottom,  is  one  of  still  greater  interest  both  to 
the  student  of  Geology  and  of  Biology. 

This  immense  rhizopod  appears  to  have  grown  one  layer 
over  another,  and  to  have  formed  reefs  of  limestone  as  do 
the  living  coral-polyps-.  Parts  of  the  original  skeleton., 
consisting  of  carbonate  of  lime,  are  still  preserved,  while 
certain  interspaces  have  been  filled  up  with  serpentine  and 
white  augite. 

Microscopic  Palaeontology. — As  a  general  role  it  is  only 
the  hard  parts  of  animal  bodies  that  have  been  preserved 
in  a  fossil  state. 

It  will  olten  occur  that  the  inspection  of  a  microscopic 
fragment  of  such  a  fossil  will  reveal  with  certainty  the 
entire  nature  of  the  organism  to  which  it  belonged.  Thus 
minute  fossil  corals,  the  spines  of  Echinodermata,  the 
eyes  of  Trilobites,  etc.,  will  determine  the  position  to 
which  we  should  ascribe  the  specimen,  or  a  section  of  tooth 
or  bone  will  enable  the  rnicroscopist  to  assign  the  fossil  to 
its  proper  class,  order,  or  family.  Thus  Professor  Owen 
identified  by  its  fossil  tooth,  the  Labyrinihodon  of  War- 
wickshire, England,  with  the  remains  in  the  Wittemberg 
sandstones,  and  declared  it  to  be  a  gigantic  frog  with  some 
resemblances  both  to  a  fish,  and  a  crocodile.  This  predic- 
tion the  subsequent  discovery  of  the  skeleton  confirmed. 

The  minute  structure  of  teeth  differs  greatly  in  differ- 
ent animals.  In  the  shark  tribe  of  fishes  the  dentine  is 
very  similar  to  bone,  excepting  that  the  lacunse  of  bone 
are  absent.  In  man  and  in  the  Garni vora  the  enamel  is  a 
superficial  layer  of  generally  uniform  thickness,  while  in 
many  of  the  Herbivora  the  enamel  forms  with  the  cemen- 
tum  a  series  of  vertical  plates  which  dip  into  the  substance 
of  the  dentine.  Enamel  is  wanting  in  serpents,  Edentata, 


98  THE    MICROSCOPIST. 

and  Cetacea.  Such  differences  make  it  quite  possible  to 
distinguish  the  affinities  of  a  fossil  specimen  from  a  small 
fragment  of  tooth. 

In  a  similar  way  the  microscopic  characters  of  bone  vary. 
The  bones  of  reptiles  and  fishes  have  the  cancellated  struc- 
ture throughout  the  shaft,  while  the  lacunae  present  very 
great  varieties,  so  that  an  animal  tribe  may  be  determined 
fcy  their  measurement.  In  this  way  many  contributions 
have  already  been  made  to  palaeontology. 


CHAPTER   VIII. 

THE   MICROSCOPE   IN   CHEMISTRY. 

THE  value  of  fnicrochemical  analysis,  and  the  simplicity 
of  its  processes,  commend  this  department  of  microscopy 
to  general  favor. 

A  large  proportion  of  the  actions  and  changes  produced 
by  reagents  may  be  observed  as  satisfactorily  in  drops  as 
in  larger  quantities.  The  decompositions  effected  by  a 
galvanic  battery  far  smaller  than  that  contained  in  a  lady's 
silver  thimble,  which  deflected  the  mirror  at  the  other  end 
of  the  Atlantic  Telegraph  Cable,  may  be  readily  observed 
with  a  microscope. 

Apparatus  and  Modes  of  Investigation. — A  few  flat  and 
hollow  glass  slides,  thin  glass  covers,  test-tubes,  small 
watch-glasses,  a  spirit-lamp  or  Bunsen's  burner,  constitute 
nearly  all  the  furniture  which  is  essential. 

Dr.  Wormley*  directs  that  a  drop  of  the  solution  to  be 
examined  should  be  placed  in  a  watch-glass,  and  a  small 
portion  of  reagent  added  with  a  pipette.  The  mixture 

*  The  Microchemistry  of  Poisons,  by  Dr.  Wormley. 


THE    MICROSCOPE    IN    CHEMISTRY.  99 

may  then  be  examined  with  the  microscope.  If  there  is 
no  precipitate,  let  it  stand  several  hours  and  examine  again. 
Dr.  Beale  prefers  a  flat  or  concave  slide,  and  suggests  that 
if  a  glass  rod  be  used  for  carrying  the  reagent,  it  must  be 
washed  each  time,  or  a  portion  may  be  transferred  from 
the  slide  to  the  bottle.  He  also  advises  the  use  of  small 
bottles  with  capillary  orifices  for  reagents.  Dr.  Lawrence 
Smith  uses  small  pipettes  with  the  open  end  covered  by 
india-rubber. 

If  heat  be  required,  the  drop  may  be  boiled  on  the  slide 
over  a  spirit-lamp,  or  a  strip  of  platinum-foil  or  mica  may 
be  held  with  forceps  so  as  to  get  a  red  or  white  heat  from 
the  lamp  or  a  Bunsen  burner.  This  is  especially  needed 
to  get  rid  of  organic  matters. 

For  the  examination  of  earthy  materials,  as  carbonate 
or  phosphate  of  lime,  phosphate  of  ammonia  and  magne- 
sia, sulphates  or  chlorides,  a  small  fragment  may  be  placed 
on  a  slide  and  covered  with  thin  glass.  •  A  drop  of  nitric 
acid  is  then  put  near  the  edge  of  the  cover.  If  bubbles 
escape  a  carbonate  is  indicated.  Neutralize  the  acid  with 
ammonia ;  let  the  flocculent  precipitate  stand  awhile ; 
cover  and  examine  with  the  microscope.  After  a  time, 
amorphous  granules  and  prisms  will  show  phosphates  of 
ammonia,  magnesia,  and  lime.  Sulphates  are  shown  by 
adding  to  the  nitric  acid  solution  nitrate  of  barytes,  and 
chlorides  by  nitrate  of  silver. 

Dr.  Beale  recommends  adding  glycerin  to  the  test  solu- 
tions. The  reactions  are  slower  but  more  perfect,  and  the 
crystalline  forms  resulting  are  more  complete. 

If  a  sublimate  be  desired,  a  watch-glass  can  be  inverted 
over  another,  and  the  lower  one  containing  the  material, 
as  biniodide  of  mercury,  etc.,  heated  over  a  spirit-lamp, 
or  the  sublimation  may  be  made  in  a  reduction-tube. 

Preparation  of  Crystals  for  the  Polariscope. — Many  speci- 
mens may  be  prepared  by  concentrating  the  solution  with 
heat  and  allowing  it  to  cool.  It  should  not  be  evaporated 


100  THE    MICROSCOPIST. 

to  dry  ness.  Many  salts  may  be  preserved  in  balsam,  but 
some  are  injured  by  it,  and  need  glycerin  or  castor  oil  as 
a  preserving  fluid. 

The  method  of  crystallization  may  be  modified  in  vari- 
ous ways  so  as  to  obtain  special  results.  Thus  if  a  solu- 
tion of  sulphate  of  iron  is  suffered  to  dry  on  a  slide,  the 
crystals  will  be  arborescent  and  fern-like,  but  if  the  liquid 
is  stirred  with  a  glass  rod  or  needle  while  evaporating, 
separate  rhombic  prisms  will  form,  which  give  beautiful 
colors-  in  the  polariscope.  Pyrogallic  acid  also  crystallizes 
in  long  needles,  but  a  little  dust,  etc.,  as  a  nucleus,  brings 
about  a  change  of  arrangement  resembling  the  "eye"  of 
the  peacock's  tail. 

A  saturated  solution  dropped  into  alcohol,  if  the  salt  is 
insoluble  in  alcohol,  will  produce  instantaneous  crystals. 

To  obtain  the  best  results,  some  crystals,  as  salicin, 
should  be  fused  on  a  slide  over  the  lamp,  and  the  matter 
spread  evenly  over  the  surface.  This  may  be  done  with 
a  hot  needle.  The  temperature  greatly  affects  the  char- 
acter of  the  crystallization.  If  very  hot,  the  crystals  run 
in  lines  from  a  common  centre.  A  medium  temperature 
produces  concentric  waves. 

Many  new  forms  result  from  uniting  different  salts  in 
different  proportions.  The  knowledge  of  these  different 
effects  can  only  be  attained  by  experience. 

Sections  of  crystals,  as  nitrate  of  potash,  etc.,  to  show 
the  rings  and  cross  in  the  polariscope,  are  difficult  to 
make.  After  cutting  a  plate  with  a  knife  to  about  one- 
fourth  of  an  inch  thick,  it  may  be  filed  with  a  wet  file  to 
one-sixth  of  an  inch,  smoothed  on  wet  glass  with  fine 
emery,  and  polished  on  silk  strained  over  a  piece  of  glass, 
and  rubbed  with  a  mixture  of  rouge  and  tallow.  The 
nitre  must  be  rubbed  till  quite  dry,  and  the  vapor  of  the 
fingers  prevented  by  the  use  of  gloves. 

For  a  general  account  of  the  use  of  polarized  light,  see 
Chapter  VI. 


THE    MICROSCOPE    IN    CHEMISTRY.  101 

The  Use  of  the  Microspectroscope. — We  have  already  de- 
scribed this  accessory  in  Chapter  III.  It  promises  im- 
portant results  in  chemical  analysis,  but  requires  delicate 
observation  and  exact  measurements,  together  with  a 
careful  and  systematic  study  of  a  large  number  of  colored 
substances. 

In  using  the  microspectroscope,  much  depends  on  the 
regulation  of  the  slit.  It  should  be  just  wide  enough  to 
give  a  clear  spectrum  without  irregular  shading.  As  a 
general  rule,  it  should  be  just  wide  enough  to  show  Frau- 
enhofer's  lines  indistinctly  in  daylight.  The  slit  in  the 
side  stage  should  be  such  that  the  two  spectra  are  of 
equal  brilliancy.  No  light  should  pass  up  the  microscope 
but  such  as  has  passed  through  the  object  under  exam- 
ination. This  sometimes  requires  a  cap  over  the  object- 
glass,  perforated  with  an  opening  of  about  one-sixteenth 
of  an  inch  for  a  one  and  a  half  inch  objective. 

The  number,  position,  width,  and  intensity  of  the  ab- 
sorption-bands are  the  data  on  which  to  form  an  opinion 
as  to  the  nature  of  the  object  -observed,  and  Mr.  Sorby 
has  invented  a  set  of  symbols  for  recording  such  observa- 
tions. (See  Dr.  Beale's  How  to  Work  with  the  Microscope.} 
These  bands,  however,  do  not  relate  so  much  to  the  ele- 
mentary constitution  as  to  the  physical  condition  of  the 
substance,  and  vary  according  to  the  nature  of  the  solvent, 
etc.,  yet  many  structures  give  such  positive  effects  as  to 
enable  us  to  decide  with  confidence  what  they  are. 

Colored  beads  obtained  by  ordinary  blowpipe  testing, 
sections  of  crystals,  etc.,  cut  wedge-shaped  so  as  to  vary 
their  thickness,  often  give  satisfactory  results.  But 
minute  quantities  of  animal  and  vegetable  substances,  as 
blood-stains,  etc.,  dissolved  and  placed  in  short  tubes 
fastened  endwise  on  glass  slides,  or  in  some  other  conve- 
nient apparatus,  offer  the  most  valuable  objects  of  re- 
search. 

To  measure  the  exact  position  of  the  absorption-bands, 


102 


THE    MICROSCOPIST. 


the  micrometer  already  described  may  be  used,  or  Mr. 
Sorby's  apparatus,  giving  an  interference  spectrum  with 
twelve  divisions,  made  by  two  Kicol's  prisms,  with  an 
intervening  plate  of  quartz  of  the  required  thickness. 

The  value  of  this  mode  of  investigation  in  medical 
chemistry,  and  for  purposes  of  diagnosis  or  jurisprudence, 
may  be  seen  by  th6  following  illustrations:* 

Pettenkofer's  Test  for  Bile  (Fig.  55).— To  a  few  drops  of 
bile  in  a  porcelain  dish,  add  a  drop  of  solution  of  cane- 


H  rr 


Pettenkofer's  Bile-Test. 


sugar,  and  then  concentrated  sulphuric  acid  drop  by  drop, 
with  agitation.  The  mixture  becomes  a  purple-red  color, 
and  shows  a  spectrum  as  in  the  figure.  The  color  will 
be  destroyed  by  water  and  alcohol. 

Tests  for  Blood. — Hsematocrystalline,  or  cruorin,  com- 
posed of  an  albuminoid  substance  and  haematin,  generally 
crystallizes  in  tetrahedra  or  octahedra.  In  blood  from 


H  ir 


Blood. 


the  horse  and  from  man'  only  an  amorphous  deposit  is 
found.  The  watery  solution  of  this  substance  properly 
diluted,  shows  two  remarkable  bands  of  absorption,  and 
obscuration  of  the  blue  and  violet  end  of  the  spectrum 
(Fig.  56).  As  the  blood  of  all  vertebrates  shows  the  same 

*  See  Thudichum  's  Manual  of  Chemical  Physiology.    New  York,  1872. 


THE    MICROSCOPE    IN    CHEMISTRY. 


103 


bands,  it  is  judged  that  hsematocrystalline  is  present  in  it 
as  such,  and  not  formed  from  it.  By  treating  a  solution 
of  blood  which  exhibits  the  two  absorption-bands  with 
hydrogen,  or  with  a  solution  of  ferrous  sulphate  contain- 
ing tartaric  acid  and  excess  of  ammonia,  taking  care  to 


A    a    7?  fJ 


H  ir 


Reduced  Hiemutocrystalline. 


exclude  the  air,  the  color  of  the  solution  changes  to  pur- 
ple, and  the  spectroscope  shows  only  one  broad  band  in- 
stead of  two  (Fig  57).  Shaking  with  air  will  restore  the 
two  bands.  By  treating  blood  with  hydrothion  or  am- 


A     n    B  C 


H   IT 


JJLJ 


Blood  treated  with  Ammonium  Sulphide. 


monium  sulphide,  three  bands  make  their  appearance,  as 
in  Fig.  58. 

Heematin  is  seen  by  the  microscope  to  consist  of  small 


H  H' 


Four  banded  Haematiu. 


rhombic  crystals.  Dissolved  in  alcohol  and  a  little  sul- 
phuric acid,  the  spectrum  shows  four,  and  under  some 
circumstances  five,  bands  (Fig.  59).  Rendered  alkaline 


104 


THE    MICROSCOPIST. 


by   caustic   potash,  one   broad   band   appears  (Fig.  60\ 
Acid  will  restore  the  former  spectrum. 

Dissolve  haernatin  in  water  with  a  little  caustic  potash. 


FIG.  60. 


A    a 


Alkaline  Ha'inatiii. 


To  a  solution  of  ferrous  sulphate,  add  tartaric  acid  and 
then  ammonia  till  alkaline.  Pour  a  little  of  the  clear 
mixture  into  the  hsematin  solution.  The  spectrum  of  re- 


A    a   B  C 


Reductd  Hiematiu. 


duced  hsematin  will  show  two  bands  (Fig,  61).     Shaking 
with  air  will  restore  the  former  spectrum. 

Lutein  Spectra. — The  juice  of  the  corpora  lutea,  to  which 
sulphuric  acid  and  a  little  sugar  is  added,  gives  a  fine 


A    a    B  C 


rr  TT 


Juice  of  (Joipura  Lutea  with  Sulphuric  Acid. 

purple  color,  and  shows  in  the  spectroscope  one  band  in 
the  green  (Fig.  62).  Its  chloroform  solution,  examined 
with  lime-light,  shows  two  bands  in  blue  (Fig.  63).  An 
alcoholic  or  ethereal  solution  gives  a  third  one  in  the 
violet. 


THE    MICROSCOPE    IN    CHEMISTRY.* 


105 


Cysto  lutein,  or  the  yellow  fluid  of  an  ovarian  cyst, 
shows  with  the  lime-light  three  hands  in  blue,  in  the 


A    a    71 


H  ir 


Chloroiorin  Solution  ol' Corpora  Lutea. 

same  position  as  the  chloroform  solution  of  lutein  (Fig. 
64). 

The  serum  of  blood,  etc.,  shows  the  bands  of  hsemato- 


A    a   B 


Cysto-Lutein  from  an  Ovarian  (Jyst. 

crystalline  and  one  or  two  doubtful  bands,  as  in  the  figure 
(Fig.  66). 

Dr.  Richardson,  of  Philadelphia,  gives  the  following 
directions  for  examining  blood-stains:  Procure  a  glass 
slide  with  a  circular  excavation,  and  moisten  the  edges 
of  the  cavity  with  a  small  drop  of  diluted  glycerin.  Lay 


A    a   B  C 


a  a  H' 


iSero-Luteiu. 


a  clean  glass  cover,  a  little  larger  than  the  excavation,  on 
white  paper,  and  put  on  it  the  smallest  visible  fragment 
of  blood-clot.  With  a  needle,  put  on  the  centre  of  the 
cover  a  speck  of  glycerin,  not  larger  than  a  full  stop  (.), 


106  THE    MICROSCOPJST. 

and  with  a  dry  needle  push  the  blood  to  the  edge  that  it 
may  be  just  moistened  with  the  glycerin.  Place  the  slide 
on  the  cover  so  that  the  glycerin  edges  of  the  cavity  may 
adhere,  and  turning  it  over,  transfer  it  to  the  stage  of  the 
microscope.  Thus  a  minute  quantity  of  a  strong  solution 
of  hsenioglobulin  is  obtained,  the  point  of  greatest  density 
of  which  may  be  found  by  a  one-fourth  objective,  and 
tested  by  the  spectroscopic  eye-piece  and  with  high  powers. 
The  tiny  drop  may  be  afterwards  wiped  off  with  moist 
blotting-paper,  and  a  little  fresh  tincture  of  guaiacum 
added,  showing  the  blue  color  of  the  guaiacum  blood-test. 
Inverted  Microscope  of  Dr.  Lawrence  Smith. — In  ordinary 
chemical  investigations  there  is  some  risk  of  injuring  the 
polish  of  the  lenses,  as  well  as  the  brass  work  of  the  mi- 
croscope, without  very  great  care.  This  is  particularly 
the  case  in  observing  the  effects  of  heat  or  of  strong  acids. 
To  obviate  this  difficulty,  Dr.  Lawrence  Smith  contrived 
a  plan  for  an  inverted  microscope,  which  has  been  con- 
structed by  Cachet  of  Paris.  The  optical  part  of  the  in- 
strument is  below  the  stage,  and  is  furnished  with  a  pecu- 
liar prism,  by  which  the  rays  from  the  objective  are  bent 
into  a  conveniently  inclined  body.  The  illuminating  ap- 
paratus is  above  the  stage.  This  construction  renders  the 

instrument  well  adapted  to;  chemical  investigations. 

• 

GENERAL  MICROCHEMICAL  TESTS. 

Dr.  Wormley  has  directed  attention  to  some  necessary 
cautions.  He  shows  that  many  substances  which  may 
readily  be  detected  in  a  pure  state,  even  in  very  minute 
quantities  by  the  microscope,  are  difficult  to  detect  when 
mixed  with  complex  organic  materials.  This  is  especially 
applicable  to  the  alkaloids,  which  should  be  separated 
from  such  mixtures  by  the  use  of  the  dialyzer— a  hoop 
with  a  bottom  of  parchment-paper,  etc. — or  extracted 
with  ether  or  chloroform. 


THE    MICROSCOPE    IN    CHEMISTRY.  107 

The  purity  of  all  reagents  should  be  carefully  estab- 
lished, and  they  should  be  kept  in  hard  German  glass 
bottles,  and  only  distilled  water  used  in  all  our  researches. 

The  true  nature  of  a  reaction  that  is  common  to  several 
substances  may  often  be  determined  with  the  microscope. 
Thus  a  solution  of  nitrate  of  silver  becomes  covered  with 
a  white  film  when  exposed  to  several  different  vapors,  but 
hydrocyanic  acid  is  the  only  one  which  is  crystalline. 
This  will  detect  100,000th  of  a  grain  of  the  acid.  A  slip 
of  clean  copper  boiled  in  a  hydrochloric  acid  solution  of 
arsenic,  mercury,  antimony,  etc.,  becomes  coated  with  the 
metal,  but  when  heated  in  a  reduction-tube,  arsenic  only 
yields  a  sublimate  of  octahedral  crystals,  and  mercury 
only  will  furnish  metallic  globules. 

A  solution  of  iodine  produces  distinct  reaction  with 
100,000th  of  a  grain  of  strychnine  in  solution  in  1  grain 
of  water,  but  as  this  is  common  to  other  alkaloids,  other 
tests  are  needed.  Yet  the  absence  of  such  a  reaction 
shows  the  absence  of  the  alkaloid. 

The  degree  of  dilution  is  important.  Thus  bromine  with 
atropin  yields  a  crystalline  deposit  from  1  grain  of  a 
20,000th  or  stronger  dilution,  but  not  with  diluter  solu- 
tions. A  limited  quantity  of  sulphuretted  hydrogen 
throws  down  from  corrosive  sublimate  a  white  deposit, 
while  excess  produces  a  black  precipitate. 

Blue  and  Reddened  Litmus  Paper  are  used  as  tests  for 
acids  and  alkalies.  It  is  a  bibulous  paper  dyed  in  infu- 
sion of  litmus.  The  red  is  made  by  adding  a  little  acetic 
acid  to  the  infusion.  Dry  substances  and  vapors  require 
the  paper  to  be  moistened  with  distilled  water.  If  the 
acid  reaction  depends  on  carbonic  acid,  warming  the  paper 
on  a  slide  over  a  lamp  will  restore  the  color.  So  if  a 
volatile  alkali,  ammonia  or  carbonate  of  ammonia,  have 
made  the  red  paper  blue,  its  color  will  be  restored  by  a 
gentle  heat.  Sometimes  the  infusion  of  litmus  is  more 
convenient  than  the  paper. 


108  THE    MICROSCOPIST. 

Alcohol  coagulates  albuminous  matter. 

Ether  dissolves  fat. 

Acetic  Acid  will  dissolve  phosphate  or  carbonate  of  lime, 
but  not  the  oxalate. 

Nitrate  of  Barytes  in  cold  saturated  solution  is  a  test  for 
sulphuric  and  phosphoric  acids.  The  precipitated  sulphate 
of  baryta  is  insoluble  in  acids  and  alkalies.  The  phosphate 
is  soluble  in  acids  and  insoluble  in  ammonia. 

Nitrate  of  Silver. — A  solution  of  60  grains  to  the  ounce 
of  water  is  a  convenient  test  for  chlorides  and  phosphates. 
Chloride  of  silver  is  white,  soluble  in  ammonia  and  insolu- 
ble in  nitric  acid.  The  tribasic  phosphate  of  silver  is  yel- 
low, and  soluble  in  excess  of  ammonia  or  of  nitric  acid. 

Oxalate  of  Ammonia  is  a  test  for  salts  of  lime.  Dissolve 
the  material  in  nitric  acid,  and  add  excess  of  ammonia. 
Dissolve  the  flocculent  precipitate  in  excess  of  acetic  acid, 
and  add  the  oxalate  of  ammonia.  Oxalate  of  lime  is  in- 
soluble in  alkalies  and  acetic  acid,  but  soluble  in  strong 
mineral  acids. 

Iodine  is  a  test  for  starch,  coloring  it  blue.  Albuminous 
tissues  are  colored  yellow,  and  vegetable  cellulose  a  brown- 
ish-yellow. The  addition  of  sulphuric  acid  turns  cellulose 
blue. 

DETERMINATION  OF  SUBSTANCES. 
ALKALIES. 

Bichloride  of  platinum  precipitates  from  salts  of  potash 
or  ammonia  a  yellow  double  chloride,  which  crystallizes 
in  beautiful  oetahedra.  It  has  no  precipitating  effect  on 
solutions  of  soda.  Polarized  light  will  distinguish  the 
800,000th  of  a  grain  of  double  chloride  of  sodium  and 
platinum  by  its  beautiful  colors  from  the  chloride  of 
potassium  and  platinum,  or  of  platinum  alone.  The 
double  chloride  of  platinum  and  potassium  may  be  dis- 
tinguished from  that  of  ammonia  by  heating  to  redness, 
treating  with  hot  water,  and  acting  on  with  nitrate  of 


THE    MICROSCOPE    IN    CHEMISTRY.  109 

silver.  The  ammonium  compound  after  ignition  leaves 
only  the  platinum,  which  gives  no  precipitate  with  nitrate 
of  silver,  while  the  potassium  chloride  yields  a  white  pre- 
cipitate of  chloride  of  silver. 

Antimoniate  of  potash  throws  down  from  solutions  of 
soda  and  its  neutral  salts  a  white  crystalline  antimoniate 
of  soda,  the  forms  of  which  vary  according  to  the  strength 
of  the  solution  ;  generally  they  are  rectangular  plates  and 
octahedra. 

ACIDS. 

Sulphuric. — In  solutions  acidulated  with  hydrochloric 
or  nitric  acid,  the  chloride  or  nitrate  of  baryta  produces 
a  white  precipitate.  Yeratrin  added  to  a  drop  of  concen- 
trated sulphuric  acid  produces  a  crimson  solution,  or  de- 
posit if  evaporated. 

Nitric. — Heated  with  excess  of  hydrochloric  acid  elimi- 
nates chlorine,  which  will  dissolve  gold  leaf.  A  blood- 
red  color  is  produced  when  nitric  acid  or  a  nitrate  is  mixed 
with  a  sulphuric  acid  solution  of  brucin. 

Hydrochloric. — Nitrate  of  silver  precipitates  amorphous 
chloride  of  silver;  soluble  in  ammonia,  but  insoluble  in 
nitric  and  sulphuric  acid. 

Oxalic. — Nitrate  of  silver  precipitates  amorphous  oxa- 
late  of  silver;  soluble  in  nitric  acid  and  also  in  solution 
of  ammonia. 

Hydrocyanic. — Put  a  drop  of  acid  solution  in  a  watch- 
glass,  invert  another  over  it  containing  a  drop  of  solution 
of  nitrate  of  silver,  and  a  crystalline  film  will  form.  A 
solution  of  hydrocyanic  acid  treated  with  caustic  potash 
or  soda  and  then  with  persulphate  of  iron  yields  Prussian 
blue. 

Phosphoric. — A  mixture  of  sulphate  of  magnesia,  chlo- 
ride of  ammonium,  and  free  ammonia  produces  in  solu- 
tions of  free  phosphoric  acid  and  alkaline  phosphates 
white  feathery  or  stellate  crystalline  precipitate  of  ammo- 


110  THE    MICROSCOPIST. 

nio-phosphate  of  magnesia.   A  slower  crystallization  gives 
prisms. 

METALLIC    OXIDES. 

These  may  usually  be  determined  by  treating  a  small 
portion  of  solution,  acidulated  with  hydrochloric  acid,  by 
sulphuretted  hydrogen ;  another,  and  neutral  portion  with 
sulphuret  of  ammonium ;  and  a  third  with  carbonate  of 
soda. 

Antimony. — Sulphuretted  hydrogen  throws  down  or- 
ange-red precipitate  from  tartar-emetic  solutions,  etc. 

Arsenic  yields  white  octahedral  crystals  of  arsenious 
acid  when  sublimed.  Arsenious  acid  may  be  reduced  to 
metallic  arsenic  by  heating  to  redness  in  a  tube  with 
charcoal  and  carbonate  of  soda.  A  solution  of  arsenious 
acid  yields  octahedral  crystals  by  evaporation,  so  as  to 
determine  with  the  microscope  1000th  to  10,000th  of  a 
grain. 

Ammonio-nitrate  of  silver  throws  down  from  an  aque- 
ous solution  of  arsenious  acid  a  bright  yellow  precipitate, 
arnmonio-sulphate  of  copper  a  green  precipitate,  and  sul- 
phuretted hydrogen  a  bright  yellow. 

Mercury. — Bichloride  of  mercury,  moistened  with  a  drop 
of  solution  of  iodide  of  potassium,  assumes  the  bright 
scarlet  color  of  biniodide  of  mercury.  A  strong  solution 
of  caustic  potash  or  soda  turns  bichloride  of  mercury  yel- 
low from  the  formation  of  protoxide ;  but  calomel  or  chlo- 
ride of  mercury  is  blackened  from  formation  of  suboxide. 
Heated  in  a  reduction-tube  with  dry  carbonate  of  soda, 
the  sublimate  shows  under  the  microscope  small,  opaque, 
spherical  globules  of  mercury.  Dr.  Wormley  states  that 
a  globule  of  mercury  or  "artificial  star"  may  be  discrim- 
inated by  the  one-eighth  objective  if  it  be  but  the 
25,000th  of  an  inch  in  diameter,  weighing  about  the 
9,000,000,000th  of  a  grain;  globules  of  g^th  of  an  inch 
diameter  weigh  about  70,000,000th  of  a  grain. 


THE    MICROSCOPE    IN    CHEMISTRY.  Ill 

Lead. — Sulphuretted  hydrogen  gives  a  black  amor- 
phous deposit.  Sulphuric  and  hydrochloric  acids  yield  a 
white  precipitate.  Chloride  of  lead  crystallizes  in  needles. 
Iodide  of  potassium  gives  a  bright  yellow  precipitate,  sol- 
uble in  boiling  water,  and  crystallizing  in  six-sided  plates. 
Bichromate  of  potassium  yields  a  bright  yellow  amor- 
phous deposit. 

Copper. — Sulphuretted  hydrogen  gives  a  brown  or  black- 
ish deposit ;  ammonia  a  blue  or  greenish-blue  amorphous 
precipitate,  or  in  dilate  solutions  a  blue  color  to  the  liquid  ; 
caustic  alkali,  a  similar  precipitate,  which  on  boiling  in 
excess  of  reagent  becomes  black,  but  if  grape-sugar,  or 
some  other  organic  agents,  be  present,  a  yellow  or  red 
precipitate  of  suboxide  of  copper  occurs.  Arsenite  of 
potassium  produces  a  bright  green. 

Zinc. — Sulphuretted  hydrogen  gives  a  white  amorphous 
deposit — the  only  white  sulphuret.  Alkalies  produce  a 
white  hydrated  oxide  of  zinc. 

ALKALOIDS. 

The  editors  of  the  Micrographic  Dictionary  refer  to  a  paper 
of  Dr.  T.  Anderson,  in  the  Edinburgh  Monthly  Journal, 
where  he  shows  that  the  microscope  readily  distinguishes 
the  more  common  alkaloids  from  each  other  by  the  form 
of  their  crystals  and  of  their  sulphocyanides.  The  alka- 
loids are  first  dissolved  in  dilute  hydrochloric  acid,  then 
precipitated  on  a  glass  plate  with  a  solution  of  ammonia, 
or  if  the  sulphocyanide  is  required,  with  a  strong  solution 
of  sulphocyanide  of  potassium.  It  may  then  be  placed 
under  the  microscope.  The  solution  should  not  be  too  con- 
centrated. This  branch  of  investigation  has  been  greatly 
promoted  by  the  elegant  work  of  Dr.  Wormley,  already 
referred  to,  on  the  Microckemistry  of  Poisons. 

Atropin. — Ammonia  throws  down  an  amorphous  pre- 
cipitate. One  grain  of  a  TJnth  grain  solution  yields  to 


112  THE    MICROSCOPIST. 

caustic  potash  or  soda  a  precipitate  which,  when  stirred 
with  a  glass  rod,  becomes  a  mass  of  crystals,  as  in  Plate 
Til,  Fig.  66.  The  Sulphocyanide  of  potassium  gives  no 
precipitate. 

Aconitin. — ]STo  characteristic  test,  except  the  physiologi- 
cal one;  j-^o^th  of  a  grain  produces  on  the  end  of  the 
tongue  a  peculiar  tingling  and  numbness,  lasting  for  an 
hour;  To0th  grain  in  alcohol,  rubbed  on  the  skin,  pro- 
duces temporary  loss  of  feeling. 

Brucin  or  Brutia. — Potash  or  ammonia  produces  stellar 
crystals.  Sulphocyanide  of  potassium,  feathery,  or  sheaf- 
like.  (Plate  III,  Fig.  67.)  Nitric  acid  produces  a  blood- 
red  color,  changing  to  yellow  by  heat.  On  cooling  the 
latter  and  adding  protochloride  of  tin,  it  becomes  a  beau- 
tiful purple.  Ferricyanide  of  potassium,  with  f  J  Dth  grain 
of  brucin  yields  the  most  brilliant  polariscope  crystals. 
(Plate  III,  Fig.  68). 

Cinchonine. — Ammonia  produces  granular  radiating 
crystals.  (Plate  III,  Fig.  69.)  Sulphocyanide  of  potas- 
sium six-sided  plates,  some  irregular.  (Plate  III,  Fig.  70.) 

Conine. — This  alkaloid  and  nicotin  are  distinguished 
from  other  alkaloids  by  being  liquid  at  ordinary  tempera- 
tures, and  by  their  peculiar  odor.  Conine  may  be  known 
from  nicotin  by  its  odor  and  sparing  solubility  in  water, 
by  yielding  crystalline  needles  to  the  vapor  or  solution  of 
hydrochloric  acid,  a  white  precipitate  with  corrosive  sub- 
limate, and  a  dark-brown  precipitate  with  nitrate  of  silver. 

Codein. — Ammonia  or  alkalies  give  a  white  amorphous 
deposit.  Sulphocyanide  of  potassium,  crystalline  needles. 
A  solution  of  iodine  in  iodide  of  potassium,  a  reddish- 
brown  precipitate,  which  becomes  crystalline.  This  is 
soluble  in  alcohol,  from  which  it  separates  in  plates  (Plate 
III,  Fig.  71),  which  appear  beautiful  in  the  polariscope. 

Dalarin. — According  to  Dr.  Wormley,  this  is  identical 
with  atropin. 

Narcotin. — In  its  pure   state   crystallizes    in  rhombic 


PLATE  III. 


FIG.  66. 


FIG.  71. 


FIG. 67. 


FIG.  68. 


c 


FIG.  72. 


FIG.  74. 


FIG.  69. 


FIG.  70. 


O 


FIG.  75. 


THE    MICROSCOPE    IN    CHEMISTRY. 

prisms,  or  oblong  plates.    Ammonia,  the  alkalies,  and  their 
carbonates  produce  tufts  of  crystals  (Plate  III,  Fig.  7'2). 
A  drop  of  aqueous  solution  of  a  salt  of  narcotin,  exposed 
to  vapor  of  ammonia,  is  covered  with  a  crystalline  film  if" 
it  only  contains  g^^th  of  its  weight  of  alkaloid. 

Morphine. — When  pure  crystallizes  in  short  rectangular 
prisms.  Sulphuric  acid  dissolves  them,  and  if  bichromate 
of  potash  be  added,  green  oxide  of  chromium  results.  Con- 
centrated nitric'acid  turns  it  orange-red,  and  dissolves  it. 
A  strong  solution  treated  with  a  strong  solution  of  nitrate 
of  silver  and  gently  heated,  decomposes  the  latter  and  pro- 
duces a  shining  crystalline  precipitate  of  metallic  silver. 
In  dilute  solutions,  alkalies  precipitate  a  crystalline  form 
(Plate  III,  Fig.  73).  No  precipitate  with  sulphocyanide 
of  potassium  unless  highly  concentrated. 

Quinine. — Amorphous  precipitate  with  ammonia.  Sul- 
phocyanide of  potassium  gives  irregular  groups  of  acicu- 
lar  crystals,  like  those  produced  by  strychnine,  but  longer 
and  more  irregular  (Plate  III,  Fig  74).  The  solution 
should  be  dilute,  and  twenty-four  hours  allowed  for  the 
crystals  to  form. 

The  iodo-disulphate,  or  Herapathite,  gives  crystals  of  a 
pale  olive-green  color,  which  possess  a  more  intense  polar- 
izing power  than  any  other  known  substance.  Dr.  Hera- 
path  proposed  this  as  a  delicate  test  for  quinine.  A  drop 
of  test-liquid — made  with  8  drachms  of  acetic  acid,  1 
drachm  of  rectified  spirits,  and  6  drops  of  dilute  sulphuric 
acid — is  placed  on  a  slide  and  the  alkaloid  added.  When 
dissolved  a  little  tincture  of  iodine  is  added,  and  after  a 
time  the  salt  separates  in  little  rosettes.  By  careful  manip- 
ulation crystals  of  this  salt  may  be  formed  large  enough 
to  replace  Mcol's  prisms  or  tourmaline  plates  in  the  polar- 
izing apparatus.  When  the  crystals  of  Herapathite  cross 
each  other  at  a  right-angle,  complete  blackness  results. 
Intermediate  positions  give  a  beautiful  play  of  colors. 

Strychnine. — Ammonia  gives  small  prismatic  crystals, 

8 


114  THE    MICROSCOPIST. 

some  crossed  at  60°  (Plate  III,  Fig.  75).  Sulphocyanide 
of  potassium  produces  flat  needles,  often  in  groups.  Iodine 
in  iodide  of  potassium  gives  a  reddish-brown  amorphous 
precipitate,  crystalline  in  dilute  solutions.  When  pure, 
strychnine  appears  in  colorless  octahedra,  lengthened 
prisms  or  granules.  To  a  solution  of  the  alkaloid  or  its 
salts  in  a  drop  of  pure  sulphuric  acid,  which  produces  no 
color,  add  a  small  crystal  of  bichromate  of  potash,  and 
stir  slowly  with  a  pointed  glass  rod.  A  blue  color  will 
appear,  passing  into  purple,  violet,  and  red.  The  bright 
yellow  crystals  of  chromate  of  strychnia,  if  dried  and 
touched  with  sulphuric  acid,  will  also  show  the  color  test. 
This  is  said  to  be  delicate  enough  to  show  TOCVoo^n  °f  a 
grain  of  strychnine.  The  tetanic  convulsions  of  frogs  im- 
mersed in  a  solution  of  strychnine,  or  after  injections  of 
the  solution  in  lungs  or  stomach,  etc  ,  is  also  a  very  deli- 
cate test. 

Veratrin  and  its  salts  treated  in  the  dry  state  with  con- 
centrated sulphuric  acid,  slowly  dissolve  to  a  reddish-yel- 
low, or  pink  solution,  which  becomes  crimson-red.  The 
process  is  accelerated  by  heat. 

Narcein,  touched  with  the  cold  acid,  becomes  brown, 
brownish-yellow,  and  greenish-yellow,  and  if  heated,  a 
dark  purple-red. 

Solanin  turns  orange-brown,  and  later  purplish-brown. 

Piperin  turns  orange-red  to  brown. 

Salicin  gives  to  the  acid  a  crimson  pink,  changing  to 
black. 

Papaverin  gives  a  fading  purple. 

CRYSTALLINE   FORMS   OF    VARIOUS   SALTS. 

Our  limits  forbid  extended  description,  yet  a  few  forms 
of  frequent  recurrence  will  be  useful  to  the  student.  For 
crystals  in  plants  or  from  animal  secretions  reference  may 
be  made  also  to  succeeding  chapters. 

Salts  of  Lim.e. — The  carbonate  sometimes  occurs  in  ani- 


PLATE  IV. 


FIG.  76. 


{ 

Q   ^ 


FIG.  77. 


,7 
i/ 


FIG.  80. 


v/ 


FIG.  81. 


FIG.  78. 


•' 


FIG.  79. 


FIG.  82. 


FIG.  83. 


THE    MICROSCOPE    IN    CHEMISTRY.  115 

mal  secretions  in  the  form  of  little  spheres  or  disks,  con- 
sisting of  groups  of  radiating  needles.  In  otoliths  it  is 
often  in  minute  hexagonal  prisms  with  trilateral  summits. 
It  is  deposited  from  water  in  irregular  forms,  all  of  which 
are  grouped  needles.  Sometimes  it  assumes  the  rhombo- 
hedral  form,  as  in  the  oyster  shell  (Plate  IV,  Fig.  76). 
In  any  doubtful  case,  test  as  described  at  pages  99  and 
108. 

Lactate  of  I^ime  gives  microscopic  crystals,  consisting  of 
delicate  radiating  needles  (Plate  IV,  Fig.  77). 

Oxalate  of  Lime  occurs  as  square  flattened  octahedra,  as 
square  prisms  with  quadrilateral  pyramids,  as  fine  needles, 
and  as  ellipsoidal  flattened  forms,  sometimes  constricted 
so  as  to  resemble  dumb-bells  (Plate  IV,  Fig.  78). 

Phosphate  of  Lime  is  usually  in  the  form  of  thin  rhombic 
plates  (Plate  IV,  Fig.  79). 

Sulphate  of  Lime  rapidly  formed,  as  in  chemical  testing, 
gives  minute  needles  or  prisms  (Plate  IV,  Fig.  80).  When 
more  slowly  formed,  these  are  larger  and  mixed  with 
rhombic  plates. 

Soda  Salts. — Chloride  of  Sodium  or  common  salt  gener- 
ally forms  a  cube,  terminated  by  quadrangular  pyramids 
or  depressions  (Plate  IV,  Fig.  81).  The  crystals  do  not 
polarize  light. 

Plate  IV,  Fig.  82,  represents  crystals  of  oxalate  of  soda, 
and  Plate  IV,  Fig.  83,  those  of  nitrate. 

Magnesia  Salts. — Ammonio-phosphate,  or  triple  phosphate, 
is  often  found  in  animal  secretions.  The  most  common 
form  is  prismatic,  but  sometimes  it  is  feathery  or  stellate 
(Plate  IV,  Fig.  84). 

Sulphate  of  Magnesia  forms  an  interesting  polarizing 
object. 

A  most  instructive  series  of  salts  may  be  made  by 
rapidly  crystallizing  some  on  glass  slides,  and  allowing 
others  to  deposit  more  slowly.  In  this  way  a  set  of  speci- 
mens may  be  prepared  for  comparison. 


116  THE    MICROSCOPIST. 

CHAPTER   IX. 

THE   MICROSCOPE   IN   BIOLOGY. 

THE  science  of  biology  (from  /?<«?,  life),  which  treats  of 
the  forms  and  functions  of  living  beings,  would  be  crude 
and  imperfect  without  the  aid  of  the  microscope.  What- 
ever might  be  learned  by  general  observation,  we  should 
miss  the  fundamental  laws  of  structure  and  the  unity 
which  we  now  know  pervades  distant  and  apparently 
different  organs,  as  well  as  distinct  species,  if  we  were 
deprived  of.  the  education  which  microscopy  gives  the 
eye  and  hand. 

The  evident  differences  between  living  and  non-living 
bodies  led  to  ancient  theories  of  life  which  are  still  influ- 
ential in  modern  thought,  but  neither  microscope  nor 
scalpel  nor  laboratory  have  revealed  the  mystery  which 
seems  ever  to  beckon  us  onward  to  another  and  entirely 
different  sphere  of  existence.  Hippocrates  invented  the 
hypothesis  of  a  principle  (</>u<rt<;,  or  nature)  which  influences 
the  organism  and  superintends  it  with  a  kind  of  intelli- 
gence, and  to  which  other  principles  (fovapets,  powers)  are 
subordinated  for  the  maintenance  of  various  functions. 
This  was  also  the  theory  of  Aristotle,  who  gave  the  name 
of  soul  (</'u%y)  to  the  animating  principle. 

Paracelsus  and  the  chemical  philosophers,  from  the 
fifteenth  to  the  seventeenth  century,  maintained  that  all 
the  phenomena  of  vitality  may  be  explained  by  chemicaj 
laws.  To  these  succeeded  the  mathematical  school  under 
Bellini  (A.D.  1645),  who  taught  that  all  vital  functions 
may  be  explained  by  gravity  and  mechanical  impulse. 
These  theories  were  supplanted  by  those  of  the  physiolo- 
gists. Van  Helmont  revived  the  Hippocratian  idea  of  a 
specific  agent,  which  he  called  archeus.  This  was  more 
fully  elaborated  by  Stahl,  who  taught  that  by  the  opera- 


THE  MICROSCOPE  IN  BIOLOGY.          117 

tion  of  an  immaterial  animating  principle  or  soul  (ammo), 
all  vital  functions  are  produced.  The  vis  medicatrix  na- 
tures of  Cullen  was  an  attempt  to  compromise  between 
the  rival  theories  of  a  superadded  principle  and  a  special 
activity  in  organized  matter  itself.* 

Harvey,  Hunter,  Miiller,  and  Prout  proposed  hypotheses 
similar  to  those  of  Aristotle  and  Hippocrates,  and  many 
modern  scientific  men  accept  similar  views.  The  recent 
doctrine  of  the  correlation  of  physical  forces  has,  however, 
revived  the  mechanical  and  chemical  theories,  and  the 
industry  with  which  these  views  have  been  propagated 
has  gained  many  adherents. 

It  is  to  be  regretted  that  philosophy  should  assume  the 
name  of  science  and  dogmatize  under  that  appellation. 
The  object  of  science  is  to  state  facts,  and  not  to  dream, 
yet  such  is  the  nature  of  man's  intellect  that  it  will  seek 
to  account  for  facts,  and  is  thus  drawn  into  metaphysical 
speculation.  If  the  age-long  controversy  between  the 
physicists  and  the  vitalists  is  ever  to  cease,  it  will  prob- 
ably be  through  the  microscopic  demonstration  of  the 
absolute  difference  between  living  and  non-living  matter. 

In  the  present  chapter  it  is  designed  to  set  forth  briefly 
the  principal  facts  of  elementary  biology  as  they  have 
been  brought  to  light  by  microscopy.  For  further  illus- 
trations in  vegetable  and  animal  histology,  reference  may 
be  made  to  following  chapters. 

1.  All  biologists  agree  that  the  elementary  unit  in  living 
bodies  is  the  cell.  This,  according  to  the  most  recent  in- 
vestigations, is  a  soft,  transparent,  colorless,  jelly-like  par- 
ticle of  matter,  which  may  be  large  enough  to  be  just  dis- 
cernible to  the  naked  eye,  or  so  small  as  to  be  invisible 
with  our  best  instruments.  The  simplest  or  most  elemen- 
tary forms  of  vegetable  or  animal  life  consist  of  single 
cells,  while  the  more  complex  organisms  are  built  up  of 

*  Compare  Bostoek's  History  of  Medicine. 


118  THE    MICROSCOPIST. 

great  numbers  of  these  cells  with  the  materials  which 
they  have  produced  and  deposited. 

Haller,  who  has  been  called  the  father  of  modern  physi- 
ology, seems  first  to  have  conceived,  though  vaguely 
(A. I).  1766),  the  idea  of  the  essential  unity  of  vital  struc- 
ture. 

In  1838,  Schleiden  and  Schwann  wrote  on  the  elemen- 
tary cell,  the  former  treating  of  the  vegetable,  and  the 
latter  of  the  animal  cell.  From  this  time  may  be  dated 
the  origin  of  the  cell  doctrine.  Much  importance  was 
assigned  to  the  distinction  between  cell- wall,  cell-contents, 
nuclei,  and  nucleoli. 

In  1835,  Dujardin  discovered  in  the  lower  animals  a 
contractile  substance  capable  of  movement,  to  which  he 
gave  the  name  of  sarcode. 

In  1861,  Max  Schultze  showed  that  sarcode  is  analo- 
gous to  the  body  or  contents  of  animal  cells,  and  that  on 
this  account  the  infusorial  animalcules  possessed  of  inde- 
pendent life  were  simple  or  compound. 

Examinations  of  this  structure  were  made  by  numerous 
observers,  and  the  identity  of  many  of  its  properties  in 
animals  and  vegetables  established.  To  this  structure 
the  name  of  protoplasm,  rather  than  sarcode,  has  been 
assigned.  As  this  term  has  been  somewhat  loosely  used, 
so  as  to  refer  to  it  either  in  the  dead  or  living  state,  Dr. 
Beale  has  proposed  the  term  bioplasm  for  elementary  struc- 
ture while  living,  and  has  given  a  generalization  from 
observed  .facts  which  has  attracted  much  attention.  He 
distinguishes  in  all  organic  forms  three  states  of  matter : 
First.  Germinal  matter  or  bioplasm,  or  matter  which  is 
living.  Second.  Matter  which  was  living,  or  formed  mate- 
rial. Third.  Matter  about  to  become  living,  or  pabulum. 

Schleiden  and  Schwann  considered  the  cell  as  a  growth 
from  a  nucleus,  and  to  consist  of  a  cell-wall  and  cavity. 
In  vegetable  cells  there  seemed  to  be  an  external  wall  of 
cellulose,  within  which  was  another,  the  primordial  utri- 


THE    MICROSCOPE    IN    BIOLOGY.  119 

cle.  But  it  has  since  been  shown  that  the  appearance  of 
the  primordial  utricle  is  caused  by  the  protoplasm  or  bio- 
plasm lying  in  apposition  with  the  inner  surface  of  the 
cell-wall.  In  the  cryptogamia,  cells  are  known  to  occur 
in  which  no  nucleus  is  visible.  Max  Schultze  and  Hackel 
have  also  discovered  non-nucleated  forms  of  animal  life. 
The  idea  of  nucleus  and  cell-wall  as  essential  to  a  cell  is 
therefore  abandoned.  Nuclei  are  regarded  as  new  centres 
of  living  matter,  or  minute  particles  of  such  matter  capa- 
ble of  independent  existence.  Some  of  these  masses  are 
so  small  as  to  be  barely  visible  with  the  one-fiftieth  objec- 
tive under  a  magnifying  power  of  five  thousand  diameters. 

2.  The  structure  and  formation  of  a  simple  cell  may  be 
illustrated  by  Plate  V,  Figs.  85  to  89,  after  Beale.*  The 
earliest  condition  of  such  a  living  particle  is  shown  in 
Plate  Y,  Fig.  85.  If  the  external  membrane  of  a  fully 
developed  spore  or  any  of  the  growing  branches  (Plate  V, 
Figs.  86  to  89)  be  ruptured,  such  particles  would  be  set 
free  in  vast  numbers. 

The  surface  of  such  a  particle  becomes  altered  by  con- 
tact with  external  agencies.  A  thin  layer  of  the  external 
surface  is  changed  into  a  soft  membrane  or  cell-wall, 
through  which  pabulum  passes  and  undergoes  conversion 
into  living  matter,  which  thus  increases.  The  increase 
of  size  is  not  owing  to  the  addition  of  new  matter  upon 
the  external  surface,  but  to  the  access  of  new  matter  in- 
teriorly. The  thickness  of  the  formed  material  depends 
on  external  circumstances,  as  temperature,  moisture,  etc. 
If  these  be  unfavorable  to  the  access  of  pabulum,  layer 
after  layer  of  living  matter  will  die  or  be  deposited,  as  in 
Plate  V,  Figs.  87  and  88.  If  such  a  cell  be  exposed  to 
circumstances  favorable  to  growth,  the  accession  of  fresh 
pabulum  will  cause  portions  of  living  matter  to  make 


*  Physiological  Anatomy  and  Physiology  of  Man,  by  Drs.  Todd,  Bow- 
man, and  Beale.     New  edition. 


120  THE    MICROSCOPIST. 

their  way  through  natural  pores  or  chance  fissures  and 
protrude,  as  in  the  figures. 

3.  The  peculiar  phenomena  of  living  cells  or  bioplasms 
may  be  classified  as  follows:  Active  or  spontaneous  move- 
ment, nutrition  and  growth,  arid  the  power  of  reproduc- 
tion. These  vital  actions,  according  to  Dr.  Beale,  occur 
in  the  bioplasm  only,  while  the  formed  material,  or  non- 
living matter,  is  the  seat  of  physical  and  chemical  changes 
exclusively.  Physical  processes,  as  diffusion  and  osmose, 
occur  in  bioplasmic  particles,  but  the  peculiar  phenomena 
referred  to,  and  which  are  properly  termed  vital,  do  not 
occur  in  non-living  matter. 

Movements  of  Cells. — Granules  imbedded  in  the  bioplasm, 
either  formed  material  or  accidental  products,  enable  our 
microscopes  to  observe  internal  movement,  while  change 
of  form  and  of  place  exhibit  the  movement  of  the  entire 
cell. 

The  granular  movement  is  either  vibratory  or  continu- 
ous. The  vibrations  of  the  granules  appear  similar  to  the 
molecular  movement  described  by  Dr.  Robert  Brown  in 
1827,  and  which  is  common  to  all  small  masses  of  matter, 
organic  or  inorganic.  Minute  cells  may  thus  dance  in 
fluid  as  well  as  fine  powders,  etc.  Such  movements  occur, 
however,  in  the  interior  of  living  cells,  and  may  possibly 
be  connected  with  vitality.  In  the  salivary  corpuscles, 
the  dancing  motion  ceases  on  the  addition  of  a  solution 
of  one-half  to  one  per  cent,  -of  common  salt,  while  such 
addition  has  no  influence  of  the  kind  on  fresh  pus  or 
lymph. 

The  continuous  granular  motion  is  either  a  relatively 
slow  progression,  corresponding  to  the  change  of  form  in 
the  cell,  or  a  swifter  flowing  movement.  Max  Schultze 
thus  describes  this  motion  in  the  threads  of  sarcode  pro- 
jected from  the  apertures  of  a  Foraminiferal  shell :  "  As 
the  passengers  in  a  broad  street  swarm  together,  so  do 
the  granules  in  one  of  the  broader  threads  make  their 


FIG.  85. 


Minute  particles  of  Bioplasm.   From 
Mildew,   ^oth  in.  Obj. 


PLATE  V. 


Passage  of  Germinal-matter  through 
pores  in  the  formed  material.    X  1800. 


FIG.  86. 


FIG. 89. 


Production  of  formed-material  on 
surface  of  Bioplasm.    X  1800. 


Production  and  accumulation  of 
Formed-material  on  Bioplasm.  Epi- 
thelium of  cuticle.  X  700. 


FIG.  87. 


FIG.  90. 


Further  production  of  formed- 
material.  At  a  is  the  budding 
Bioplasm,  passing  through  pores 
in  the  formed-material.  X  1800. 


Amoeboe  from  organic  infusion. 


THE    MICROSCOPE    IN    BIOLOGY.  121 

way  by  one  another,  oftentimes  stopping  and  hesitating, 
yet  always  pursuing  a  determinate  direction  correspond- 
ing to  the  long  axis  of  the  thread.  They  frequently  be- 
come stationary  in  the  middle  of  their  course,  and  then 
turn  round,  but  the  greater  number  pass  to  the  extreme 
end  of  the  thread,  and  then  reverse  the  direction  of  their 
movement."  No  physical  or  chemical  action  with  which 
we  are  acquainted  will  account  for  such  motions,  which 
have  no  analogy  in  unorganized  bodies. 

Changes  of  form  are  most  strongly  marked  in  the  lower 
forms  of  animal  life,  although  occurring  also  in  the  sim- 
pler vegetables,  as  the  volvox.  The  Amoeba  or  Proteus  is 
typical  of  such  changes,  which  have  hence  been  termed 
Amoeboid  (Plate  V,  Fig.  90).  When  an  Amoeba  meets 
another  animal  which  is  too  slow  to  escape,  it  sends  out 
projections  which  encircle  its  prey ;  these  coalesce,  and 
invest  the  whole  mass  with  its  bioplasm.  It  maintains 
its  grasp  till  it  has  abstracted  all  the  portions  which  are 
soluble,  and  then  relaxes  its  hold. 

Amoeboid  cells  in  higher  animals  rarely  move  so  rapidly 
as  the  Amoeba  itself.  Their  motions  are  limited  to  a 
gradual  change  of  form  or  to  the  protrusion  of  processes 
in  the  form  of  threads,  or  tuberosities,  or  tufts,  which 
either  drag  the  rest  of  the  body  after  them  or  are  again 
withdrawn. 

Cells  of  bioplasm  may  not  only  change  their  form,  but 
may  wander  from  place  to  place  by  protruding  a  portion 
of  their  mass,  which  drags  the  rest  after  it.  The  discov- 
ery of  wandering  cells  in  the  higher  organisms,  as  man, 
has  opened  quite  a  new  and  important  field  of  physiologi- 
cal and  pathological  research. 

The  movements  of  bioplasm  may  be  changed,  acceler- 
ated, retarded,  or  stopped  by  a  variety  of  stimuli,  mechani- 
cal, electrical,  chemical,  and  nervous.  Gentle  warmth  and 
moisture  are  necessary  to  their  perfection.* 

*  See  Strieker's  Manual  of  Histology. 


THE    MIGROSCOPIST. 

The  nutrition  and  growth  of  the  living  cell  has  already 
been  described  as  the  conversion  of  pabulum  into  bioplasm 
or  living  matter.  The  subject  of  reproduction  will  be  ex- 
amined below  under  the  head  of  reU-geneste. 

4.  The  microscopic  demonstration  of  bioplasm,  may  be 
effected  by  the  use  of  an  alkaline  solution  of  coloring 
matter,  as  carmine.  (See  Chapter  V.)     As  bioplasm  pos- 
sesses an  acid  reaction,  the  alkali  is  neutralized  and  the 
color  retained.     This  process,  however,  is  rather  a  dem- 
onstration of  the  protoplasm  which  was  recently  alive. 
For  living  cells  or  bioplasm,  we  must  depend  on  supplying 
them  artificially  with  colored  food.    Thus  indigo,  carmine, 
etc,,  in  fine  particles,  added  to  the  pabulum  of  cells  or 
liquid  media  in  which  they  float,  will  be  taken  into  the 
interior  of  the  bioplasm  by  the  nutritive  process.     In  this 
way  Recklinghausen  showed  the  migration  of  pus-corpus- 
dea 

Welcker  and  Osborne  were  the  first  to  use  a  solution 
of  carmine  in  order  to  stain  the  nuclei  of  tissues.  They 
were  followed  by  Gerlach  and  Beale,  the  latter  of  whom 
has  greatly  improved  the  process  and  shown  its  signifi- 
cance. 

5.  The  chemistry  of  cells  and  their  products  is  an  essential 
part  of  biology,  but  would  lead  us  too  far  from  our  subject 
to  discuss,  yet  a  few  points  may  not  be  irrelevant. 

The  chemical  composition  of  bioplasm  consists  essen- 
tially of  oxygen,  hydrogen,  nitrogen,  and  carbon.  Other 
elements  are  often  present  and  important,  but  not  essen- 
tial. Of  the  relation  of  these  elements  we  know  nothing, 
save  that  they  are  in  a  state  of  constant  vibration  or 

change.    Dr.  Beale  considers  it  doubtful  if  ordinarv  chemi- 

• 

cal  combination  is  possible  while  the  matter  lives.  Analy- 
sis-in  the  laboratory  is  only  possible  with  the  compounds 
resulting  from  the  death  of  the  cell. 

When  living  or  germinal  matter  is  converted  into  formed 
material,  a  combination  of  its  elements  takes  place,  often 


THE   MICROSCOPE   IK   BIOLOGY*  12  i 

u }  t  h  very  complex  resul  ts,  the  nature  of  which  has  hitherto 
baffled  the  efforts  of  chemists  to  determine.  When  the 
life  of  <^>r\\\\\\'<>.\  rmxt.Urr.  Jjowovor.  i-.  .-.u<l<k-ri!y  <]<:~rroy^i. 
or  rather  when  the  matter  is  first  transformed,  the  com- 
pounds resulting  from  various  species  have  similar  chemi- 
cal composition  and  properties,  and  an  acid  reaction  is 
<\<;\-<:\<>l><:<\.  Fi \,ri n .  ?j.i \j\i u\<:\\ ,  v/nt <:r.  fcn'l  ^ruin  MlU  rnfAV 
thus  be  obtained  from  every  kind  of  germinal  matter. 
Fatty  matters  also  result,  which  continue  to  increase  in 
quantity  for  some  time  after  death.  In  slow  molecular 
death,  a  certain  amount  of  oxygen  is  taken  into  combina- 
tion, which  ^ives  rise  to  different  results  from  those  which 
occur  when  life  is  suddenly  destroyed.  Still  other  com- 
binations are  due  to  vital  actions  which  are  not  yet  under- 
stood. Thus  some  bioplasm  produces  muscle;  other  par- 
ticles originate  nerve  structure,  cartilage,  bone,  connective 
tissue,  etc.  Many  chemical  changes  occur  also  in  formed 
material  after  its  production.  It  may  become  dry  or  fluid, 
or  split  up  into  gaseous  or  soluble  substances  as  soon  as 
produced.  Imperfect  oxidation  may  lead  to  the  formation 
of  fatty  matters,  uric  acid,  oxalatcs,  sugar,  etc.  At  the 
earliest  period  of  development,  the  formed  material  con- 
sists principally  of  albuminous  and  fatty  matters,  with 
chlorides,  alkaline  and  earthy  phosphates.  At  a  later 
period  gelatin,  with  amyloid  or  starchy  matter,  is  pro- 
duced.* 

6.  Varieties  in  the  Form,  and  Function  of  Bioptsirrn,. — 
Mutability  of  shape  is  characteristic  of  amoeboid  cells, 
and  no  conclusions  can  be  drawn  from  their  appearance 
after  death.  Where  numbers  of  them  are  accumulated, 
they  are  flattened  by  mutual  pressure  so  as  to  appear 
polyhedral,  laminated,  or  prismatic.  The  upper  layers  of 
laminated  epithelium  are  usually  flattened.  Where  cells 
line  the  interior  of  cavities  in  a  single  layer,  they  form 

*  See  Physiological  Anatomy,  by  Todd,  Bowman,  and  Beale. 


124  THE    MICROSCOPIST. 

plates  of  different  shape  (endothelial  cells\  or  cells  in  which 
the  long  axis  predominates  (cylindrical  epithelium),  or 
forms  which  are  intermediate  between  plates  and  cylin- 
ders. Some  cells  appear  ramified  or  stellate,  as  in  the 
cells  from  the  pith  of  a  rush,  bone-cells,  and  corpuscles  of 
the  cornea.  Others  may  become  extraordinarily  elongated, 
as  in  the  formation  of  fibre,  muscle,  etc.  Some  cells  are 
provided  with  cilia,  which  are  limited  to  one  portion  of 
the  surface,  and  project  their  free  extremities  into  the 
cavity  which  they  line.  Dr.  Beale  considers  the  cilia  to 
be  formed  material,  and  their  movements  not  vital,  but  a 
result  of  changes  consequent  on  vital  phenomena. 

Every  living  organism,  plant,  animal,  or  man,  begins 
its  existence  as  a  minute  particle  of  bioplasm.  Every 
organic  form,  leaves,  iiowers,  shells,  and  all  varieties  of 
animals;  and  every  tissue,  cellular,  vesicular,  hair,  bone, 
skin,  muscle,  and  nerve,  originates  by  subdivision  and 
multiplication  and  change  of  bioplasm,  and  the  trans- 
formation or  metamorphosis  of  bioplasm  into  formed  ma- 
terial. It  is  evident,  therefore,  that  there  are  different 
kinds  of  bioplasm  indistinguishable  by  physics  and  chem- 
istry, but  endowed  with  different  powers.* 

7.  Cell-Genesis. — Schleiden  first  showed  that  the  em- 
bryo of  a  flowering  plant  originates  in  a  nucleated  cell, 
and  that  from  such  cells  all  vegetable  tissues  are  devel- 
oped. The  original  cells  were  formed  in  a  plasma  or  blas- 
tema, commonly  found  in  pre-existing  cells,  the  nuclei  first 
appearing  and  then  the  cell-membrane.  These  views  were 
applied  by  Schwann  to  animal  structure.  The  latter  be- 
lieved that  the  extra-cellular  formation  of  cells,  or  their 
origin  in  a  free  blastema,  was  most  frequent  in  animals. 
The  researches  of  succeeding  physiologists  have,  however, 
led  to  a  general  belief  that  all  cells  originate  from  other 
cells. 

*  Beale's  Bioplasm. 


THE    MICROSCOPE    IN    BIOLOGY.  125 

The  doctrine  of  spontaneous  generation  or  abiogenesis 
has  been  the  object  of  considerable  research,  but  the  bril- 
liant experiments  of  Pasteur  have  shown  that  when  all 
access  of  living  organisms  into  fluids  is  prevented,  no  de- 
velopment of  such  organisms  can  be  proved  in  any  case 
to  occur.  If  the  access  of  air,  for  instance,  to  a  liquid 
which  has  been  boiled,  is  filtered  through  a  plug  of  cotton- 
wool, no  living  forms  will  appear  in  the  liquid,  but  on 
examination,  such  forms  will  be  found  in  considerable 
numbers  in  the  cotton-wool,  proving  the  presence  of  these 
forms  or  their  germs  in  the  external  air.  Recent  experi- 
ments also  render  it  probable  that  some  cell-germs  are 
indestructible  by  a  heat  far  exceeding  that  of  boiling 
water. 

There  are  three  forms  of  cell-multiplication,  by  fission, 
by  germination  or  budding,  and  by  internal  division.  The 
latter  mode  is  termed  endogenous.  In  it  new  cells  are 
produced  within  a  parent-cell  by  the  separation  of  the 
bioplasm  into  a  number  of  distinct  masses,  each  of  which 
may  become  a  new  cell,  as  in  the  fecundated  ovum. 

Fission,  or  the  division  by  cleavage  of  a  parent-cell  into 
two  or  four  parts,  may  be  regarded  as  a  modification  of 
endogenous  cell-multiplication.  A  good  example  of  it 
may  be  seen  in  cartilage. 

Budding  or  germination  consists  in  the  projection  of  a 
little  process  or  bud  from  the  mass  of  bioplasm,  which  is 
separated  by  the  constriction  of  its  base,  and  becomes  an 
independent  cell. 

8.  Reproduction  in  the  higher  organisms  consists  essen- 
tially of  the  production  of  two  distinct  elements,  a  germ- 
cell  or  ovum,  and  a  sperm-cell  or  spermatozoid,  by  the 
contact  of  which  the  ovum  is  enabled  to  develop  a  new 
individual.  Sometimes  these  elements  are  produced  by 
different  parts  of  the  same  organism,  in  which  case  the 
sexes  are  said  to  be  united,  and  the  individual  is  called 
hermaphrodite,  androgynous,  or  monoscious.  In  other  in- 


126  THE    MICROSCOPIST. 

stances  the  sexes  are  distinct,  and  the  species  are  called 
dioecious. 

9.  The  alternation  of  generations  is  a  term  given  in  bi- 
ology to  express  a  form  of  multiplication  which  occurs  in 
some  of  the  more  simple  forms  of  life.     It  consists  really 
of  the  alternation  of  a  true  sexual  generation  with  the 
phenomenon  of  budding.     Thus  a  fern  spore  gives  rise,  by 
budding  and  cell-division,  to  a  prothallium ;  this  produces 
archegonia  and  antheridia,  as  the  sexual  elements  are 
called,  and  the  embryo  which  results  from  sexual  union 
produces  not  a  prothallium  but  a  fern.     This  phenomenon 
is  better  seen  in  the  Hydrozoa.     In  these  the  egg  produces 
a  minute,  ciliated,  free-swimming  body,  which  attaches 
itself,  becomes  tapering,  develops  a  mouth  and  tentacles, 
and  is  known  as  the  Hydra  tuba.     This  multiplies  itself, 
and  produces  extensive  colonies  by  germination,  but  under 
certain  circumstances   divides   by   fission   and   produces 
Medusas,  which  develop  ova. 

10.  Parthenogenesis  designates  the  production  of  new 
individuals  by  virgin  females  without  the  intervention  of 
a  male.     It  has  also  been  applied  to  germination  and 
fission  in  sexless  beings.     In  the  Aphides, ova,  are  hatched 
in  spring,  but  ten  or  more  generations  are  produced  vi- 
viparously  and  without  sexual  union  throughout  the  sum- 
mer.    In  autumn,  however,  the  final  brood  are  winged 
males  and  wingless  females,  from  whose  union  ova  are 
produced  in  the  ordinary  manner. 

11.  Transformation  and  metamorphosis  relate  to  certain 
changes  or  variations  of  development  in  the  structure  and 
life  history  of  an  individual.     Thus  an  insect  is  an  egg  or 
ovum,  a  caterpillar  or  larva,  a  pupa  or  chrysalis,  and  an 
imago  or  perfect  insect,  and  these  changes  of  condition 
and  structure  constitute  its  development.    Much  difficulty 
is  caused  by  the  phenomena  of  metamorphosis  in  assign- 
ing the  place  of  different  species,  transformations  being 
often  mistaken  for  specific  differences.     It  was  formerly 


THE  MICROSCOPE  IN  BIOLOGY.          127 

supposed  that  every  animal  passed  through,  in  its  devel- 
opment, a  series  of  stages  in  which  it  resembled  the  infe- 
rior members  of  the  animal  scale,  and  systems  of  zoology 
were  proposed  to  be  founded  on  this  dream  of  embryology. 
Careful  research,  however,  has  shown  that  larval  changes 
present  many  variations.  In  some  the  young  exhibit  the 
conditions  of  adults  of  lower  animals.  Thus  the  Edis,  a 
univalve  shell  fish,  in  its  young  state  has  all  the  charac- 
teristics of  a  Pteropod,  a  free-swimming  mollusk.  Some- 
times development  is  retrograde,  and  the  adult  is  a  de- 
graded form  as  compared  with  the  larva,  thus  setting  at 
nought  all  our  theories,  and  teaching  us  that  it  is  better 
to  observe  than  to  imagine. 

12.  Discrimination  of  Living  Forms. — We  have  seen, 
section  6,  that  there  are  different  kinds  of  living  matter 
endowed  with  different  powers.  We  have  also  seen,  sec- 
tion 7,  how  varied  are  the  forms  of  multiplication.  Yet 
when  we  come  to  discriminate  between  animal  and  vege- 
table life,  we  find  it  exceedingly  difficult,  especially  in 
their  more  simple  forms.  Neither  form,  nor  chemical 
composition,  nor  structure,  nor  motive  power,  affords  suf- 
ficient grounds  for  discrimination.  Yet  when  we  consider 
the  functions  of  bioplasm  in  its  varied  forms,  we  may  con- 
veniently group  all  living  beings  in  three  great  divisions, 
viz.,  fungi,  plants,  and  animals. 

The  bioplasm  of  the  plant  finds  its  pabulum  in  merely 
inorganic  compounds,  while  that  of  the  animal  is  prepared 
for  it,  directly  or  indirectly,  by  the  vegetable.  The  func- 
tion of  fungi  appears  to  be  the  decomposition  of  the  formed 
material  of  plants  and  animals  by  the  means  of  fermenta- 
tion or  putrefaction,  since  these  latter  processes  are  depen- 
dent on  the  presence  of  fungi.  Thus  by  bioplasm  are  the 
structures  of  plants  and  animals  reared  from  inorganic 
materials,  and  by  bioplasm  are  they  broken  down  and 
restored  to  the  inanimate  world. 


128  THE    MICROSCOPIST. 

CHAPTER    X. 

THE   MICROSCOPE    IN   VEGETABLE   HISTOLOGY    AND    BOTANY. 

HISTOLOGY  (from  fa™?,  a  tissue)  treats  of  formed  mate- 
rial, or  the  microscopic  structure  resulting  from  the  trans- 
formation of  germinal  or  living  matter.  The  nature  of 
this  transformation  is  partly  physical  and  partly  vital, 
and,  as  already  stated,  is  often  so  complex  as  to  baffle  all 
chemical  analysis.  Some  light,  however,  has  been  thrown 
on  this  subject  by  the  modification  of  ordinary  crystalline 
forms  when  inorganic  particles  aggregate  in  the  presence 
of  certain  kinds  of  organic  matter.  To  this  mode  of  form- 
ation the  name  of  molecular  coalescence  has  been  given. 
Mr.  Rainey  and  Professor  Harting  contemporaneously 
experimented  with  solutions  of  organic  colloids,  and  found 
that  the  crystallization  of  certain  lime  salts,  as  the  car- 
bonate, "was  so  modified  by  such  solutions  as  to  resemble 
many  of  the  calcareous  deposits  found  in  nature.  These 
researches  leave  little  doubt  but  that  a  majority  of  calca- 
reous and  silicious  organic  forms  may  be  thus  accounted 
for.  Such  changes  are  rather  physical  than  vital. 

Cell-substance  in  Vegetables. — The  protoplasm  or  bio- 
plasm in  vegetable-cells  cannot  be  distinguished  from  ani- 
mal usarcode"  or  protoplasm  except  by  the  nature  of  the 
pabulum  or  aliment  necessary  to  its  nutrition.  The  vege- 
table, under  the  stimulus  of  light,  decomposes  carbonic 
acid,  and  acquires  a  red  or  green  color  from  the  compounds 
which  it  forms,  while  the  animal  requires  nutriment  from 
pre-existing  organisms.  Yet  this  definition  fails  to  apply 
to  fungi,  which  resemble  primitive  animals  even  in  this 
respect.  So  difficult  is  it  to  discriminate  that  the  simpler 
forms  of  vegetables  have  often  been  classed  by  naturalists 
among  animals,  and  vice  versa.  Amoeboid  movements 
have  been  observed  in  the  bioplasm  of  vegetable-cells, 


THE    MICROSCOPE    IN    HISTOLOGY    AND    BOTANY.      129 

especially  in  the  Volvox,  and  some  have  considered  it 
probable  that  an  organism  may  live  a  truly  vegetable  life 
at  one  period  and  a  truly  animal  life  at  another. 

Analogous  to  amoeboid  movements,  is  the  motion  of 
bioplasmic  fluid  in  the  interior  of  undoubtedly  vegetable 
cells.  This  movement  is  called  cydosis,  and  may  be  de- 
tected under  the  microscope  by  the  granules  or  particles 
which  the  current  carries  with  it  in  the  transparent  cells 
of  Chara,Vallisneria,  etc.,  and  in  the  epidermic  hairs  of 
many  plants,  as  Tradescantia,  Plantago,  etc.  (Plate  VI, 
Fig.  91). 

The  bioplasm  of  plants  may  be  stained  with  carmine 
solution  without  affecting  the  cell-wall  or  other  formed 
material. 

Cell-wall  or  Membrane. — Plants,  whether  simple  or 
complicated  in  structure,  are  but  cells  or  aggregations  of 
cells.  In  the  simplest  vegetables  or  Protophytes,  each  cell 
lives  as  it  were  an  independent  life,  performing  every 
function;  while  in  the  higher  plants,  as  the  palm  or  oak, 
the  cells  undergo  special  modifications,  and  serve  various 
functions  subsidiary  to  the  life  of  the  plant  as  a  whole. 

Cell-membrane,  or  the  envelope  of  formed  material,  was 
formerly  thought  to  be  composed  of  two  layers,  to  the 
inner  one  of  which  the  name  of  primordial  utricle  was 
given,  but  this  is  now  considered  to  be  but  the  external 
surface  of  the  bioplasm  or  germinal  matter. 

The  chemical  nature  of  cell-membrane  is  nearly  identi- 
cal with  starch,  being  composed  of  cellulose.  The  presence 
of  cellulose  may  be  shown  by  the  blue  color  which  is 
produced  by  applying  iodine  and  sulphuric  acid,  or  the 
iodized  solution  of  chloride  of  zinc. 

Endosmose  will  take  place  in  cell-membrane,  allowing 
solutions  to  pass  through,  as  pabulum,  and  the  manner  of 
this  passage  may  in  some  instances  determine  the  subse- 
quent deposit  of  formed  material.  Sometimes  actual  pores 
are  left  in  the  membrane,  as  in  Sphagnum  (Plate  VI,  Fig. 


130  THE    MICROSCOPIST. 

92).  The  walls  of  vegetable-cells  are  often  thickened  by 
deposit.  If  this  is  in  isolated  patches,  the  cells  are  called 
dotted  (Plate  VI,  Fig.  93),  and  it  is  sometimes  difficult  to 
distinguish  them  from  porous  cells.  Many  cells  have  a 
spiral  fibre  (Plate  VI,  Fig.  94),  which  appears  to  have 
been  detached  from  the  outer  membrane.  In  the  seeds  of 
Collomia,  etc.,  the  cell- wall  is  less  consolidated  than  the 
deposit,  so  that  on  softening  the  cells  by  water,  the  spiral 
fibres  suddenly  spring  out,  making  a  beautiful  object  for 
a  half-inch  object-glass  (Plate  VI,  Fig.  95). 

The  tendency  of  formed  material  to  arrange  itself  in  a 
spiral  is  seen  in  the  endochrome  of  many  of  the  simpler 
plants, as  Zygnema,a,n&  the  cell-wall  sometimes  tears  most 
readily  in  a  spiral  direction. 

If  the  spiral  deposit  is  broken  and  coalesces  at  some  of 
its  turns,  it  forms  an  annulus  or  ring.  Some  cells  show 
both  rings  and  spirals. 

For  the  production  of  a  spiral  movement  or  growth, 
another  force  is  needed  in  addition  to  the  centripetal  and 
centrifugal  forces  which  are  necessary  for  curvilinear  mo- 
tion. The  centripetal  point  must  be  carried  forward  in 
space  by  a  progressive  force.  When  we  consider  that  a 
spiral  form  is  so  frequently  seen  in  morphology,  that  the 
secondary  planets  move  in  spirals  round  their  primaries, 
and  that  even  in  distant  nebulae  the  same  law  prevails, 
we  are  struck  with  the  unity  of  plan  which  is  exhibited 
throughout  the  universe,  and  can  scarcely  £ail  to  observe 
that  even  a  microscopic  cell  shows  the  tracings  of  the  same 
divine  handiwork  which  swings  the  stars  in  their  courses. 

Sclerogen  —  Ligneous  Tissue.  —  Sometimes  the  deposit 
within  the  cell-wall  is  of  considerable  thickness,  and  often 
in  concentric  rings,  through  which  a  series  of  passages  is 
left  so  that  the  outer  membrane  is  the  only  obstacle  to 
the  access  of  pabulum,  as  in  the  stones  of  fruit,  gritty  tis- 
sue of  the  pear,  etc.  (Plate  VII,  Fig.  96).  The  nature  of 
this  deposit  is  similar  to  cellulose,  although  often  contain- 


PLATE  VI. 


FIG.  91. 


K,o.», 

'•i.r  * 


Dotted  cells-pith  of  Elder. 


FIG.  94. 


Circulation  of  fluid  in  hairs  of  Tradescantia 
Virginica. 


Spiral  cells  : — A,  Balsam  ;  B,  c, 
Pleurothallis. 


FIG.  92. 


Portion  of  the  leaf  of  Sphagnum. 


Spiral  fibres  of  seed-coat  of  Collomia. 


THE    MICROSCOPE    IN   HISTOLOGY    AND    BOTANY.      131 

ing  resinous  and  other  matters.  Woody  fibre  or  ligneous 
tissue  is  quite  similar,  save  that  the  cells  have  become 
elongated  or  fusiform,  and  when  completely  filled  up  with 
internal  deposit,  fulfil  no  other  purpose  than  that  of  me- 
chanical support  (Plate  VII,  Fig.  97).  The  woody  fibres 
of  the  Coniferce  exhibit  peculiar  markings,  which  have 
been  called  glandular  (Plate  VII,  Fig.  98).  In  these  the 
inner  circle  represents  a  deficiency  of  deposit  as  in  other 
porous  cells,  while  the  outer  circle  is  the  boundary  of  a 
lenticular  cavity  between  the  adjacent  cells.  This  ar- 
rangement is  so  characteristic  as  to  enable  us  to  determine 
the  tribe  to  which  a  minute  fragment,  even  of  fossil  wood, 
belonged. 

Spiral  Vessels. — If  spiral  cells  are  elongated,  or  coalesce 
at  their  ends,  they  become  vessels,  some  of  which  convey 
air  and  some  fluid  (Plate  VII,  Fig.  99).  As  in  cells,  the 
want  of  continuity  in  the  spiral  fibre  sometimes  produces 
rings,  when  the  duct  is  called  annular.  In  other  instances 
the  spires  are  still  more  broken  up  by  the  process  of  growth, 
so  as  to  form  an  irregular  network  in  the  duct,  which  is 
then  said  to  be  reticulated.  A  still  greater  variation  in 
the  deposit  produces  dotted  ducts.  Not  infrequently  we 
find  all  forms  in  the  same  bundle  of  vessels. 

Laticiferous  Vessels  (Plate  VII,  Fig.  100).— These  con- 
vey the  milky  juice  or  latex  of  such  plants  as  possess  it, 
as  the  Euphorbiacese,  india-rubber  plant,  etc.,  and  differ 
from  the  ducts  above  described  by  their  branching,  so  as 
to  form  a  network,  while  ducts  are  straight  and  parallel 
with  each  other. 

The  laticiferous  vessels  resemble  the  capillary  vessels  of 
animals,  while  the  spiral  ducts  remind  us  of  the  trachea 
of  insects. 

Siliceous  Structures. — The  structures  of  many  plants, 
especially  the  epidermis,  often  become  so  permeated  with 
a  deposit  of  silica,  that  a  complete  skeleton  is  left  after 
the  soft  vegetable  matter  is  destroyed.  The  frustules  of 


132  THE    MICROSCOPIST. 

Diatoms  have  in  this  way  heen  preserved  in  vast  numbers 
in  the  rocky  strata  of  the  earth.  The  markings  on  these 
siliceous  shells  are  so  delicate  as  to  be  employed  as  a  test 
of  microscopic  power  and  definition.  In  a  species  of 
Equisetum  or  Dutch  rush,  silica  exists  in  such  abundance 
that  the  stems  are  sometimes  employed  by  artisans  as  a 
substitute  for  sand-paper.  If  such  a  stem  is  boiled  and 
macerated  in  nitric  acid  until  all  the  softer  parts  are  de- 
stroyed, a  cast  of  pure  silica  will  exhibit  not  only  the 
forms  of  the  epidermic  cells,  but  details  of  the  stomata  or 
pores.  The  same  also  is  true  of  the  husk  of  a  grain  of 
wheat,  etc.,  in  which  even  the  fibres  of  the  spiral  vessels 
are  silicified.  The  stellate  hairs  of  the  siliceous  cuticle 
from  the  leaf  of  Deutzia  scabra  forms  a  beautiful  polari- 
scope  object. 

FORMED  MATERIAL  WITHIN  VEGETABLE  CELLS. 

1.  Raphides. — These  are  crystalline  mineral  substances, 
principally  oxalate,  citrate,  and  phosphate  of  lime.     They 
occur  in  all  parts  of  the  plant,  sometimes  in  the  form  of 
bundles  of  delicate  needles,  sometimes  in  larger  crystals, 
and  sometimes  in  stellate  or  conglomerate  form.     Mr.  E. 
Quekett  produced  such  forms  artificially  by  filling  the 
cells  of  rice-paper  with  lime-water  under  an  air-pump,  and 
then  placing  the  paper  in  weak  solutions  of  phosphoric  or 
oxalic  acid. 

2.  Starch. — This  performs  in  plants  a  similar  function 
to  that  of  fat  in  animals,  and  is  a  most  important  ingre- 
dient in  human  food,  since  two-thirds  of  mankind  subsist 
almost  exclusively  upon  it.     It  is  found  in  the  cells  of 
plants  in  the  form  of  granules  or  secondary  cells.     Each 
granule  under  the  microscope  shows  at  one  extremity  a 
circular  spot  or  hilum,  around  which  are  a  number  of 
curved  lines,  supposed  to  be  wrinkles  in  the  cell-membrane. 
When  starch  is  boiled  in  water,  this  membrane  bursts  and 


PLATE  VII. 


Spiral  vessels: — A,  reticulated;  B,  old 
vessel,  with  perforations;  c,  D,  spiral 
vessels,  becoming  annular. 


FIG.  97. 


FIG. 100. 


Wood-fibre-flax 


Lactiferous  vessels. 


FIG.  98. 


FIG. 101. 


Section  of  Coniferous  Wood  in  the 
direction  of  the  fibres. 


Cubical 


al  parenchyma,  with  stellate 
from  petiole  of  Nuphar  lutea. 


stellate  cells, 


THE    MICROSCOPE    IN    HISTOLOGY    AND    BOTANY.      133 

the  amylaceous  matter  is  dissolved.  Iodine  stains  starch 
blue.  Starch  shows  in  the  polariscope  a  black  cross  in 
each  grain,  changing  to  white  as  the  prism  is  revolved. 

3.  Chlorophyll  is  the  green  coloring  matter  of  plants. 
It  is  usually  seen  in  the  form  of  granules  of  bioplasm  in 
the  interior  of  cells.     These  green  granules  yield  their 
chlorophyll  to  alcohol  and  ether.     It  seems  to  be  neces- 
sary to  nutrition,  since  green  plants  under  the  stimulus 
of  light  break  up  carbonic  acid  into  oxygen  and  carbon, 
the  latter  of  which  is  absorbed. 

The  red  and  yellow  color  of  autumn  leaves  is  owing  to 
the  chemical  metamorphosis  of  chlorophyll,  as  also  is  the 
red  color  of  many  of  the  lower  Algae,  etc.  In  the  latter 
it  seems  to  be  in  some  way  connected  with  the  vital  pro- 
cesses. 

4.  The  coloring  matter  of  flowers  is  various,  and  ordinarily 
depends  on  the  colored  fluid  contained  in  cells  subjacent 
to  the  epidermis,  although  sometimes  it  is  in  the  form  of 
solid  corpuscles.    White  patches  on  leaves,  etc.,  arise  from 
absence  of  chlorophyll. 

5.  Milky  juices  are  true  secretions  contained  in  the  lati- 
ciferous  ducts.     The  juice  of  the  dandelion,  caoutchouc 
or  india-rubber,  which  is  the  concrete  juice  of  Hie  Ficus 
elastica,  and  gutta-percha,  from  Isonandra  gutla,  are  exam- 
ples. 

6.  Fixed  oils  are  found  in  the  cells  of  active  tissues,  and 
notably  in  seeds,  where  they  serve  to  nourish  the  embryo. 
Cocoanut,  palm,  castor,  poppy,  and  linseed  oils  are  exam- 
ples. 

7.  Volatile  oil,  sometimes  called  essential  oil,  is  chiefly 
found   in   glandular   cells   and   hairs   of   the   epidermis. 
Many  of  them  yield  a  resinous  substance  by  evaporation. 

8.  Camphor  is  analogous  to  volatile  oil,  although  solid 
at  ordinary  temperatures.     It  abounds  in  the  Lauracese. 

9.  Resin,  wax,  and  tallow  are  also  found  in  plants.     The 
bloom  of  the  plum  and  grape  is  due  to  wax. 


134  THE    MICROSCOPIST. 

10.  Gum  is  a  viscid  secretion.  What  is  called  gum 
tragacanth,  is  said  to  be  partially  decomposed  cell-mem- 
brane, and  is  allied  to  amyloid  matter. 

Forms  of  Vegetable  Cells. — From  the  account  given  in 
the  chapter  on  biology,  page  123,  it  is  evident  that  the 
form  of  cells  is  quite  varied,  and  often  depends  on  the 
amount  of  pressure  from  aggregation,  yet  function  also 
has  much  to  do  in  the  determination  of  shape.  Thus 
while  most  elongated  cells  are  lengthened  in  the  direction 
of  plant-growth,  in  which  is  least  resistance,  the  medul- 
lary rays  of  Exogenous  stems  are  elongated  in  a  horizon- 
tal direction.  Some  cells  are  cubical,  as  in  the  leaves  of 
the  yellow  water-lily,  Nuphar  lutea  (Plate  VII,  Fig.  101). 
Others  are  stellate,  as  in  the  rush  (Plate  VIII,  Fig.  102). 
In  many  tissues  are  large  cavities  or  air-chambers  alto- 
gether void  of  cells,  and  in  leaves  such  cavities  communi- 
cate with  the  external  air  by  means  of  stomata  or  pores 
(Plate  VIII,  Fig.  103),  which  are  usually  provided  with 
peculiar  cells  for  contracting  or  widening  the  orifice. 

The  Botanical  Arrangement  of  Plants. — Considered  with 
reference  to  their  general  structure,  plants  are  divided  by 
botanists  into  cellular  and  vascular.  The  first  of  these 
classes  is  of  greatest  interest  to  the  microscopist,  as  em- 
bracing the  minuter  forms  of  vegetable  life. 

The  classification  and  natural  grouping  of  plants  is  yet 
far  from  being  perfect,  although  microscopic  examinations 
have  largely  contributed  to  an  orderly  arrangement  of  the 
multitudinous  varieties  in  this  field  of  research.  In  the 
present  work  we  propose  only  a  brief  outline  of  typical 
subjects  of  interest,  with  the  methods  of  microscopic  ex- 
amination. 

Fungi. — At  page  127  it  was  stated  that  all  living  beings 
may  be  grouped  in  three  divisions,  fungi,  plants,  and 
animals.  Botanists  generally  class  fungi  among  cellular 
flowerless  plants.  They  cannot  assimilate  inorganic  food 
as  other  plants,  but  live  upon  the  substance  of  animal  or 


PLATE  VIII. 


Fiu.  102. 


Section  of  cellular  parenchyma  of  Rush. 


Portion  of  the  cuticle  of  the  leaf  of  the  Iris 
Germanica,  torn  from  its  surface. 


FIG.  104. 


Cells  from  the  petal  of  the  Geranium 
( Pelargon  ium). 


Cuticle  of  leaf  of  Indian  Corn  (Zea  mais). 


THE    MICROSCOPE    IN    HISTOLOGY    AND    BOTANY.      135 

vegetable  tissue.  They  also  differ  from  ordinary  vegeta- 
bles by  the  total  absence  of  chlorophyll  or  its  red  modifi- 
cation. A  large  number  of  this  strange  class  are  micro- 
scopic, and  require  high  powers  for  their  observation. 
Recent  investigations  show  that  individual  fungi  are  de- 
veloped in  very  dissimilar  modes,  and  are  subject  to  a 
great  variety  of  form,  rendering  it  probable  that  those 
which  seem  most  simple  are  but  imperfectly  developed; 
forms.  Amoeboid  motions  also  in  the  cell-substance  of 
certain  kinds  of  fungi,  and  the  projection  of  threads  of 
bioplasm,  show  a  great  resemblance  to  some  of  the  lower 
forms  of  animal  life,  as  the  Rhizopods. 

All  fungi  exhibit  two  well-defined  structures,  a  myce- 
'lium  or  vegetative  structure,  which  is  a  mass  of  delicate 
filaments  or  elongated  cells ;  and  a  fruit  or  reproductive 
structure,  which  varies  in  different  tribes.  In  Tornla,  one 
•or  more  globular  cells  are  produced  at  the  ends  of  fila- 
ments composed  of  elongated  cells;  these  globules  drop 
off  and  become  new  mycelia.  The  "yeast  plant,"  or  Torula 
cerevisia  (Plate  IX,  Fig.  107),  receives  its  name  from  its 
habitat.  Fermentation  depends  upon  its  presence,  as  pu- 
trefaction does  upon  the  minute  analogous  bodies  called 
Bacteria  and  Vibriones.  Bacteria  are  minute^  moving, 
rod-like  bodies,  sometimes  jointed  ;  and  vibriones  are 
moniliform  filaments,  having  a  vibratile  or  wriggling  mo- 
tion across  the  field  of  view  in  the  microscope.  The  re- 
searches of  Madame  Luders  render  it  probable  that  the 
germs  of  fungi  develop  themselves  into  these  bodies  when 
sown  in  water  containing  animal  matter,  and  into  yeast 
in  a  saccharine  solution.  The  universal  diffusion  of  spor- 
ules  of  fungi  in  the  atmosphere  readily  accounts  for  their 
appearance  in  such  fluids,  and  Pasteur's  experiments  are 
quite  conclusive. 

The  minute  molecules  called  microzymes,  present  in  va- 
rious products  of  disease,  as  the  vaccine  vesicle,  fluid  of 
glanders,  etc. ;  the  minute  corpuscles  which  cause  the  dis- 


136  THE    MICROSCOPIST. 

ease  among  silkworms  called  "pebrine;"  etc.;  have  a 
strong  analogy  in  their  rapid  multiplication  to  the  yeast- 
cells. 

The  sporules  of  any  of  the  ordinary  moulds,  as  Penicil- 
lium,  Mucor,  or  Aspergillus,  will  develop  into  yeast-cells 
hi  a  moderately  warm  solution  of  cane-sugar,  showing 
how  differently  the  same  type  of  bioplasm  may  develop 
under  different  conditions.  The  term  polymorphism  has 
been  given  to  this  phenomenon.  Very  many  species,  and 
even  genera,  so  called,  may  after  all  be  only  varieties  of 
the  same  kind  of  organism. 

In  many  morbid  conditions  of  the  skin  and  mucous 
membranes,  there  is  not  only  an  alteration  or  morbid 
growth  of  the  part,  but  a  vegetation  of  fungi.  Thrown- 
off  scales  of  epithelium  from  the  mouth  and  fauces  exhibit 
fibres  of  leptothrix,  and  the  false  membrane  of  diphtheria, 
as  well  as  the  white  patches  of  aphtha  or  thrush,  show 
the  mycelia  and  spores  of  fungi.  The  disease  in  silkworms 
called  muscardine  is  due  to  a  fungus,  the  Botrytis  bassiana 
(Plate  VIII,  Fig.  104),  whose  spores  enter  and  develop  in 
the  air-tubes.  The  filamentous  tufts  seen  about  dead  flies 
on  window-panes,  etc.,  arise  from  a  similar  growth  of 
Achyla.  In  certain  Chinese  or  Australian  caterpillars, 
this  sort  of  growth  becomes  so  dense  as  to  give  them  the 
appearance  of  dried  twigs.  Even  shells  and  other  hard 
tissues  may  become  penetrated  by  fungi.  The  dry  rot  in 
timber  is  a  form  of  fungus. 

The  mildew  which  attacks  the  straw  of  wheat,  etc., 
arises  from  the  Puccinia  graminis,  whose  spores  find  their 
way  through  the  stomata  or  breathing  pores  of  the  epi- 
dermis. Rust,  and  smut,  and  bunt,  originate  in  varieties 
of  Vredo.  The  "vine  disease"  and  the  "potato  disease," 
as  they  are  called,  have  similar  origin. 

Various  methods  have  been  proposed  to  destroy  fungi 
in  growing  plants,  but  it  must  be  remembered  that  the 
function  of  these  organisms  is  chiefly  to  remove  formed 


PLATE  IX. 


FIG.  107. 


FIG. 109. 


Germ  and  Sperm-cells  in  Achyla. 


Torufa  Cerevisice,  or  Yeast-Plant. 


Development  of  fungi:  A,  mycelium;  B,  hypha;  c,  conidiophores;  D,  a  magnified  branch. 


FIG.  110. 


ft** 


Various  phases  of  development  of  Palmoglcea  macrococca. 


THE    MICROSCOPE    IN    HISTOLOGY    AND    BOTANY.       137 

material  in  a  state  of  decay,  which  is  more  or  less  com- 
plete. The  prevalence  of  atmospheric  changes,  variations 
in  light,  heat,  moisture,  and  electricity,  etc.,  have  much 
to  do  in  predisposing  vegetable  as  well  as  animal  tissues  to 
disease  and  producing  epidemics.  The  agriculturist,  there- 
fore, as  well  as  the  physician,  must  discriminate  between 
those  diseased  conditions  which  provide  a  habitat  for 
fungi,  and  the  effects  produced  by  the  fungi  themselves. 

Impregnating  wood  with  corrosive  sublimate  or  chlo- 
ride of  zinc  has  been  used  to  prevent  dry  rot  in  wood,  and 
soaking  seeds  in  alkaline  solutions  or  sulphate  of  copper 
is  said  to  remove  smut  and  similar  fungus  spores. 

The  development  of  fungi  is  from  spores  or  conidia. 
Plate  IX,  Fig.  107,  represents  the  Torula  vegetating  by 
the  budding  of  its  spores.  These  buds  rapidly  fall  off  and 
become  independent  cells.  In  other  varieties  self-division 
gives  rise  to  the  mycelium,  a  mass  of  fibres  often  inter- 
laced so  as  to  form  a  sort  of  felt.  Some  branches  of  this 
mycelium  (hyphce)  hang  down,  while  others  rise  above  the 
surface  (conidiophores)  and  bear  conidia,  which  fall  off  and 
develop  into  new  hyphee  (Plate  IX,  Fig.  108).  In  the 
"blight"  of  the  potato  the  mycelium  is  loose,  and  the 
hyphae  ramify  in  the  intercellular  spaces  and  give  off  pro- 
jections into  the  cells  of  the  plant.  The  conidia  germinate 
by  bursting  the  sac  which  contains  them,  putting  forth 
cilia,  moving  awhile,  then  resting  and  enveloping  them- 
selves with  membrane  and  growing  into  hyphse.  In  the 
autumn,  parts  of  the  hyphae  assume  special  functions. 
One  part  develops  a  spherical  mass  called  oogonium,  while 
another  becomes  a  smaller  mass  or  antheridium.  When 
the  first  is  ripe,  it  is  penetrated  by  the  latter,  and  the 
bioplasms  of  each  are  fused  together.  The  antheridium 
then  decays,  while  the  oogonium  grows  and  becomes  au 
oospore,  in  which  the  bioplasm  divides  and  subdivides. 
Next  season  each  segment  escapes  ciliated,  and  moves 
about  till  it  finds  a  place  to  germinate.  In  Achyla  two 


138  THE    MICROSCOPIST. 

sacs  are  formed,  one  of  which  contains  "germ-cells,"  and 
the  other  antherozoids  or  "sperm-cells."  When  both  are 
ripe  the  sac  opens,  and  the  ciliated  antherozoids  pass  into 
the  neighboring  sac  and  fertilize  its  contents  (Plate  IX, 
Fig.  109). 

In  other  fungi  the  reproductive  cells  are  undistinguish- 
able  from  the  rest,  and  the  coalescence  takes  place  in  a 
new  cell  formed  by  the  union  of  the  other  two. 

Mr.  Berkeley  divides  fungi  into  six  orders,  as  follows : 

1.  Hymenomycetes  or  Agaricoidece,  (Mushrooms,  etc.). — 
Mycelium   flocuose,  inconspicuous,  bearing  fleshy  fruits 
which  expand  so  as  to  expose  the  hymenium  or  sporifer- 
ous  membrane  to  the  air.     Spores  generally  in  fours  on 
short  pedicles. 

2.  Gasteromycetes  or  Lycoperdoidece  (Puff  balls,  etc.). — 
Fruit  globular  or  oval,  with  convolutions  covered  by  the 
hymenium,  which  bears  the  spores  in  fours  on  distinct 
pedicles.     The  convolutions  break  up  into  a  pulverulent 
or  gelatinous  mass. 

3.  Coniomycetes  or  Uredoidece  (Smuts,  etc.). — Mycelium 
filamentous,  parasitic.     Microscopic  fructification  of  ses- 
sile or  stalked  spores  in  groups,  sometimes  septate. 

4.  Hyphomycetes  or  Botrytoidew  (Mildews,  etc.). — Micro- 
scopic.    Mycelium  filamentous,  epiphytic,  with  erect  fila- 
ments bearing  terminal,  free,  single,  simple,  or  septate 
spores. 

5.  Ascomycetes  or  Helvelloidece  (Truffles,  etc.). — Myce- 
lium inconspicuous.     Fruit  fleshy,  leathery,  horny,  or  ge- 
latinous, lobed,  or  warty,  with  groups  of  elongated  sacs 
(asci  or  thecce)  in  which  the  spores  (generally  eight)  are 
developed. 

6.  Physomycetes   or   Mucoroidece   (Moulds).  —  Mycelium 
(microscopic)  filamentous,  bearing  stalked  sacs  containing 
numerous  minute  sporules. 

Protophytes,  or  primitive  plants,  afford  many  forms  and 
groups  of  great  interest  to  the  microscopist  as  well  as  to 


THE    MICROSCOPE    IN    HISTOLOGY    AND    BOTANY.      139 

the  biologist.  The  plan  of  the  present  work  permits  us 
only  to  indicate  a  few  particulars,  the  details  of  which 
would  form  a  volume  of  considerable  size. 

The  Algae  are  divided  into  three  orders:  I.  Ehodosper- 
mece  or  Floridce  (Red-spored  Algce).  Marine  plants,  with 
a  leaf-like  or  filamentous  rose-red  or  purple  thallus.  •  II. 
Melanosporece  or  Fucoidece  (Dark-spored  Algce).  Marine. 
Thallus  leaf-like,  shrubby,  cord-like,  or  filamentous,  of 
olive-green  or  brown  color.  III.  Chlorosporece  or  Confer- 
voidece  (Green-spored  Algce).  Plants  marine  or  fresh  water, 
or  growing  on  damp  surfaces.  Thallus  filamentous,  rarely 
leaf-like,  pulverulent,  or  gelatinous.  These  have  been 
subdivided  into  families,  viz. : 

I.  Hhodospermece. — 1.  Rhodomelacese.   2.  Laurenciacese. 
3.  Corallinacese.      4.  »Delesseriacea3.     5.  Rhodymeniacese. 
6.  Cryptonemiacese.     7.  Ceramiaceae.     8.  Porphyraceaa. 

II.  Melanosporece. — 1.  Fucaceaa.      2.  Dietyotaceaa.  3. 
Cutleriaceaa.    4.  Laminariaeeaa.    5.  Dictyosiphonaceaa.  6. 
Punctariaceaa.      7.  Sporochnaceaa.     8.  Chordariaceaa.  9. 
Myrionemacese.     10.  Ectocarpacese. 

III.  Chlorosporece. — 1.  Lemaneeae.    2.  Batrachospermeae. 
3.  Choatophoraceee.      4.   Confervacese.      5.   Zygnemaceae. 
6.  CEdogoniacese.     7.  Siphonaceae.    8.  Oscillatoriacese.    9. 
E"ostochace83.     10.  Ulvacese.     11.  Palmellaceae.     12.  Des- 
midiacese.     13.  Diatomaceea.     14.  Yolvocineee. 

For  fuller  information,  we  refer  to  the  Micrographic 
Dictionary  by  Griffith  and  Henfrey. 

In  the  family  of  Palmellacece  we  find  the  simplest  forms 
of  vegetation  in  the  form  of  a  powdery  layer  of  cells,  or  a 
slimy  film,  or  a  membranous  frond.  The  green  mould  on 
damp  walls  and  the  red  snow  of  alpine  regions  are  exam- 
ples. 

In  the  green  slime  on  damp  stones,  etc.,  is  found  the 
Palmoglcea  macrococca.  The  microscope  shows  it  to  con- 
sist of  cells  containing  chlorophyll,  surrounded  by  a  ge- 
latinous envelope.  These  cells  multiply  by  self-division. 


.140  THE    MICROSCOPIST. 

Sometimes  a  conjugation  or  fusion  of  cells  occurs,  and  the 
product  is  a  spore  or  primordial  cell  of  a  new  generation 
(Plate  IX,  Fig.  110).  During  conjugation  oil  is  produced 
in  the  cells,  and  the  chlorophyll  disappears  or  becomes 
brown,  and  when  the  spore  vegetates,  the  oil  disappears 
and  green  granular  matter  takes  its  place.  This  is  analo- 
gous to  the  transformation  of  starch  into  oil  in  the  seeds 
of  the  higher  plants. 

Most  of  the  lower  forms  of  vegetable  life  pass  through 
what  is  called  the  motile  condition,  which  depends  on  the 
extension  of  the  bioplasm  into  thread-like  filaments,  whose 
contractions  serve  to  move  the  cell  through  the  water. 
Many  of  these  forms  were  formerly  mistaken  for  animal- 
cules, and  the  transformation  of  a  portion  of  green  chlo- 
rophyll into  the  red  form  was  represented  as  an  eye.  The 
multiplication  of  the  "still"  cells  is  by  self-division,  as  in 
Palmoglwa,  but  after  this  has  been  repeated  about  four 
times,  the  new  cells  become  furnished  with  cilia  and  pass 
into  the  "  motile  "  condition,  and  their  multiplication  goes 
on  in  different  ways,  as  by  binary  or  quaternary  segmen- 
tation, or  the  formation  of  a  compound,  mulberry-like 
mass,  the  ciliated  individual  cells  of  which,  becoming  free, 
rank  as  zoospores  (Plate  X,  Fig.  111). 

The  Volvox  is  a  beautiful  example  of  the  composite 
motile  form  of  elementary  vegetation.  It  is  found  in 
fresh  water,  and  consists  of  a  hollow  pellucid  sphere, 
studded  with  green  spots,  connected  together  often  by 
green  threads.  Each  of  these  spots  has  two  cilia,  whose 
motions  produce  a  rolling  movement  of  the  entire  mass. 
Within  the  sphere  there  are  usually  from  two  to  twenty 
smaller  globes,  which  are  set  free  by  the  bursting  of  the 
original  envelope.  Sometimes  one  of  the  masses  of  endo- 
chrome  enlarges,  but  instead  of  undergoing  subdivision 
becomes  a  moving  mass  of  bi9plasm,  which  cannot  be  dis- 
tinguished from  a  true  Amoeba  or  primitive  animal  cell. 

The  Desmidiacece  are  a  family  of  minute  green  plants 


PLATE  X. 


Various  phases  of  development  of  Protococcus  pluvialis. 


Formation  of  Zouspores  in  Phycoseris  gfgantea  (Ulva  latissiuia). 


THE    MICROSCOPE    IN    HISTOLOGY    AND    BOTANY.      141 

of  great  interest.  Generally  the  cells  are  independent, 
but  a  filament  is  sometimes  formed  by  binary  subdivision. 
Their  symmetrical  shape,  and  frequently  spinous  projec- 
tions and  peculiar  movements,  render  them  beautiful  ob- 
jects. By  conjugation  a  spore-cell  or  sporangium  is  pro- 
duced, which  in  some  species  is  spinous,  and  resembles 
certain  fossil  remains  in  flint,  which  have  been  described 
as  animalcules  under  the  name  of  Xanthidia. 

The  family  of  Diatomacece  affords  more  occupation  to 
microscopists  than  other  protophytes.  Like  the  Desmids, 
they  are  simple  cells  with  a  firm  external  coating,  but  in 
Diatoms  this  coating  is  so  penetrated  with  silex,  that  a 
cast  of  the  frustule  is  left  after  the  removal  of  the  organic 
matter.  Reference  has  already  been  made  to  the  number 
of  these  organisms  in  a  fossil  state,  as  well  as  to  their 
utility  as  tests  of  the  defining  power  of  microscopic  object- 
glasses. 

Some  species  inhabit  the  sea,  and  others  fresh  water. 
They  are  so  numerous  that  scarcely  a  ditch  or  cistern  is 
free  from  specimens,  and  they  multiply  so  rapidly  as  to 
actually  diminish  the  depth  of  channels  and  block  up 
harbors.  They  may  be  sought  for  in  the  slimy  masses 
attached  to  rocks  and  plants  in  water,  in  the  scum  of  the 
surface,  in  mud  or  sand,  in  guano,  in  the  stomachs  of 
molluscs,  etc.,  arid  on  sea-weeds. 

To  separate  the  shields  or  siliceous  frustules  from  foreign 
matter,  either  fresh  or  fossil,  they  should  be  washed  sev- 
eral times  in  water,  and  the  sediment  allowed  to  subside. 
The  deposit  should  then  be  treated  in  a  test-tube  with 
hydrochloric  acid,  sometimes  aided  by  heat.  This  should 
be  repeated  as  often  as  any  effect  is  produced,  and  then 
the  sediment  should  be  boiled  in  strong  nitric  acid,  and 
washed  several  times  in  water.  They  may  be  mounted 
dry  or  in  balsam. 

The  classification  of  Diatoms  is  not  yet  perfected,  but 
Muller's  type  slides,  containing  from  one  hundred  to  five 


142  THE    MICROSCOPIST. 

hundred  characteristic  forms,  is  a  valuable  assistance. 
The  following  table,  from  the  Micrographic  Dictionary, 
gives  an  analysis  of  tribes  and  genera :  Fr.  denotes  the 
frustules  in  front  view;  v.  the  valves;  granular  striae 
means  striae  resolvable  into  dots ;  and  continuous  striae 
signify  costae  or  caualiculse. 

A.  Frustules  not  contained  in  a  Gelatinous  Mass  or  Tube. 

TRIBE  I.  STRIAE. — Frustules  usually  transversely  stri- 
ate,  but  neither  vittate  nor  areolate. 

f  Valves  without  a  Median  Nodule. 

COHORT  1.  EUNOTIEJE. — Fr.  arcuate,  single,  or  united 
into  a  straight  filament. 

1.  Epithemia. — Fr.  single  or  binate,  with  transverse  or 
slightly  radiant  striae,  some  continuous ;  no  terminal  nod- 
ules; aquatic  and  marine. 

2.  Eunotia* — Fr.  single  or  binate;  v.  with  slightly  ra- 
diant granular  striae  and  terminal  nodules;  aquatic. 

3.  -Himantidium. — Fr.  as  in  Eunotia,  but  united  into  a 
filament;  striae  parallel,  transverse;  aquatic. 

COHORT  2.  MERIDE.E. — Fr.  cuneate,  single,  or  united 
into  a  curved  or  spinal  band;  v.  with  continuous  or  gran- 
ular striae. 

4.  Meridion. — Fr.  cuneate,  united  into  a  spiral  band; 
striae  continuous ;  aquatic. 

5.  Eucampia. — Fr.  united  into  an  arched  band ;  v.  punc- 
tate; marine. 

6.  Oncosphenia. — Fr.  single,  cuneate,  uncinate  at  the 
narrow  end;  striae  granular;  aquatic. 

COHORT  3.  FRAGILLARIEJE. — Fr.  quadrilateral,  single,  or 
united  into  a  filament  or  chain;  v.  with  continuous  or 
granular  striae. 

7.  Diatom  a. — Fr.  linear  or  rectangular,  united  by  the 


THE    MICROSCOPE    IN    HISTOLOGY    AND    BOTANY.      143 

angles  so  as  to  form  a  zigzag  chain;  striae  continuous; 
aquatic  and  marine. 

8.  Aster ionella. — Fr.  adherent  by  adjacent  angles  into 
a   star-like   filament;   v.  inflated   at  one  or  both  ends; 
aquatic. 

9.  Fragillaria. — Fr.  linear,  united  into  a  straight,  close 
filament ;  striae  granular,  faint ;  aquatic  and  marine. 

10.  Denticula. — Fr.  linear,  simple,  or  binate,  rarely  more 
united;  striae  continuous;  aquatic. 

11.  Odontidium. — As  Denticula,  but  fr.  forming  a  close 
filament ;  aquatic  and  marine. 

COHORT  4.  MELOSIRE^:. — Fr.  cylindrical,  disk-shaped  or 
globose;  v.  punctate,  or  often  with  radiate  continuous 
or  granular  striae. 

12.  Cydotella. — Fr.   disk-shaped,   mostly    solitary;    v. 
with  radiate  marginal  striae ;  aquatic. 

13.  Melosira. — Fr.  cylindrical  or  spherical,  united  into 
a  filament ;  v.  punctate,  or  with  marginal  radiate  granu- 
lar striae;  aquatic  and  marine. 

14.  Podosira. — Fr.  united  in  small  numbers,  cylindrical 
or  spherical,  fixed  by  a  terminal  stalk;  v.  hemispherical, 
punctate;  marine. 

15.  Mastogonia. — Fr.  single;  v.  unequal,  angular,  mam- 
miform, circular  at   base,  without   umbilical   processes ; 
angles  radiating;  fossil. 

'  16.  Pododiscus. — Fr.  single  or  united,  with  a  marginal 
stalk ;  v.  circular,  convex. 

17.  Pyxidicula. — Fr.  single  or  binate,  free  or  sessile; 
v.  convex  ;  aquatic  and  marine. 

18.  Stephanodiscus. — Fr.  single,  disk-shaped;   v.  circu- 
lar, equal,  punctate,  'or  striate,  wTith  a  fringe  of  minute 
marginal  teeth ;  aquatic. 

19.  Stephanogonia. — Fr.  as  in  Mastogonia,  but  ends  of 
valves  truncate,  angular,  and  spinous;  fossil. 

20.  Hercotheca. — Fr.  single,  turgid   laterally ;   v.  with 
marginal  free  setae. 


144:  THE    MICROSCOPIST. 

21.  Goniothecium. — Fr.  single,  constricted  in  the  middle, 
suddenly  attenuate  and  truncate  at  the  ends  (hence  appear- 
ing angular). 

COHORT  5.  SURIRELLEJE. — Fr.  single  or  binate,  quadri- 
lateral, oval,  or  saddle-shaped,  sometimes  constricted  in 
the  middle;  v.  with  transverse  or  radiating  continuous 
or  granular  striae,  interrupted  in  the  middle,  or  with  one 
or  more  longitudinal  rows  of  puncta;  often  keeled. 

22.  Bacillaria. — Fr.  prismatic,  straight,  at  first  forming 
a  filament;  v.  with  a  median  longitudinal  row  of  puncta; 
marine. 

23.  Campylodiseus. — Fr.    single,   free,   disk-shaped;   v. 
curved  or  twisted  (saddle-shaped  i;  aquatic  and  marine. 

24.  Doryphora. — Fr.  single,  stalked ;   v.  lanceolate  or 
elliptical,  with  transverse  granular  striae. 

25.  Podocystis. — Fr.  attached,  sessile;  v.  with  a  median 
line,  transverse   continuous,  and   intermediate   granular 
striae. 

26.  Nitzschia. — Fr.  free,  single,  compressed,  usually  elon- 
gate, straight,  curved,  or   sigmoid,  with   a   not-median 
keel,  and   one   or  more   longitudinal   rows   of    puncta ; 
aquatic  and  marine. 

27.  Sphinctocystis ( Cymato pleura). — Fr.  free, single, linear, 
with  undulate  margins;  v.  oblong  or  elliptical, sometimes 
constricted  in  the  middle;  aquatic. 

28.  Surirella. — Fr.  free,  single,  ovate,  elliptical,  oblong, 
cuneate,  or  broadly  linear ;  v.  with  a  longitudinal  median 
line  or  clear  space,  margins  winged,  and  with  transverse 
or  slightly  radiating  continuous  striae ;  aquatic  and  marine. 

29.  Synedra. — Fr.  prismatic,  rectangular,  or  curved ;  at 
first  attached  to  a  gelatinous-lobed  cushion,  often  becom- 
ing free;  v.  linear  or  lanceolate,  usually  with  a  median 
pseudo-nodule  and  longitudinal  line ;  aquatic  and  marine. 

30.  Tryblionella. — Fr.  free,  linear,  or  elliptical ;  v.  plane, 
with  a  median  line,  transverse  striae,  and  submarginal  or 
obsolete  alae ;  aquatic  and  marine. 


THE    MICROSCOPE    IN    HISTOLOGY    AND    BOTANY.      145 

31.  Raphoneis. — Doryphora  without  a  stalk. 

COHORT  6.  AMPHIPLEURE^E. — Fr.  free,  single,  straight, 
or  slightly  sis;moid ;  v.  lanceolate,  or  linear-lanceolate-, 
with  a  median  longitudinal  line. 

32.  Amphi pleura. — Characters  as  above. 


ft  Valves  with  a  Median  Nodule. 

COHORT  7.  COCCONEID.E. — Fr.  straight  or  bent,  attached 
by  the  end  or  side;  v.  elliptical,  equilateral. 

33.  Cocconeis. — Fr.  single,  compressed,  adnate;  v.  ellip- 
tical, one  of  them  with  a  median  line. 

COHORT  8.  ACHNANTHE.E. — Fr.  compressed,  single,  or 
rarely  united  into  a  straight  filament,  curved,  attached 
by  a  stalk  at  one  angle;  uppermost  v.  with  a  longitudinal 
median  line,  lower  v.  the  same,  and  a  stauros  or  transverse 
line;  marine. 

35.  Achnanthidium. — Fr.  those  of  Achnanthes,  but  free; 
aquatic. 

36.  Cymbosira. — Fr.  as  Achnanthes,  solitary  or  binate, 
stipitate,  and  attached  end  to  end ;  marine. 

COHORT  9.  CYMBELLE^:. — Fr.  straight  or  curved,  free  or 
stalked  at  the  end ;  v.  inequilateral,  not  sigmoid. 

37.  Cymbella. — Fr.  free,  solitary;  v.  navicular,  with  a 
subcentral  and  two  terminal  nodules,  and  a  subrnedian 
longitudinal  line;  aquatic. 

38.  Cocconema. — Fr.  as  Cymbella,  but  stalked;  aquatic. 
COHORT  10.  GOMPHONEME^I. — Fr.  wedge-shaped,  straight, 

free,  or  stalked  ;  v   equilateral. 

39.  Gomphonema. — Fr.  single  or  binate,  wedge-shaped, 
attached  by  their  ends  to  a  stalk;  v.  with  a  median  line, 
and  a  median  and  terminal  nodules;  aquatic. 

40.  8phenella. — Fr.  free,  solitary,  wedge-shaped,  invo- 
lute; aquatic. 

10 


146  THE    MICROSCOPIST. 

41.  Sphenosira. — Fr.  united  into  a  straight  filament;  v. 
wedge-shaped,  at  one  end  rounded,  suddenly  contracted 
and  produced ;  aquatic. 

COHORT  11.  NAVICULEJE.— Fr.  free,  straight;  v.  equilat- 
eral, or  sometimes  sigmoid. 

42.  Navicula. — Fr.  single,  free,  straight;  v.  oblong, lan- 
ceolate, or  elliptical,  with  a  median  line,  a  central  and  two 
terminal  nodules,  and  transversely  or  slightly  radiant  lines 
resolvable  into  dots ;  aquatic,  marine,  and  fossil. 

43.  Gyrosigma  (Pleurosigmd). — Fr.  as  Navicula,  but  v. 
sigmoid ;  aquatic  and  marine. 

44.  Pinnularia. — Fr.  as  Navicula,  but  transverse  lines 
continuous ;  aquatic  and  marine. 

45.  Stauroneis. — Fr.  as  Navicula,  but  the  median  line 
replaced  by  a  stauros ;  aquatic  and  marine. 

46.  Diadesmis. — Fr.  as  Navicula,  united  into  a  straight 
filament;  aquatic. 

47.  Amphiprora. — Fr.  free,  solitary,  or  in  pairs,  con- 
stricted in  the  middle;  v.  with  a  median  keel,  and  a 
median  and  terminal  nodules,  often  twisted ;  marine. 

48.  Amphora. — Fr.  plano-convex,  elliptical,  oval  or  ob- 
long, solitary,  free  or  adnate,  with  a  marginal  line,  and  a 
nodule  or  stauros  on  the  flat  side ;  aquatic  and  marine. 


TRIBE  II.  VITTATJE.—  Fr.  with  vittee. 

t  Valves  without  a  Median  Nodule. 

COHORT  12.  LICMOPHORE^E. — Fr.  cuneate;  vittfe  arched. 

49.  Licmophora. — Fr.  cuneate,  rounded  at  the  broad 
end,  radiating  from  a  branched  stalk;  vittse  curved  (by 
inflection  of  upper  margins  of  valves) ;  marine. 

50.  Podosphenia. — Fr.  as  Licmophora,  but  single  or  in 
pairs,  sessile  on  a  thick  but  little  branched  pedicle;  ma- 
rine. 


THE    MICROSCOPE    IN    HISTOLOGY    AND    BOTANY.      147 

51.  Rhipidophora. — Fr.  as  Licmophora,  single  or  in  pairs, 
on  a  branched  stipes ;  marine. 

52.  Climacosphenia. — Fr.  cuneate,  rounded  at  broad  end, 
divided  into  loculi  by  transverse  septae  or  vittae ;  marine. 

COHORT  13.  STRIATELLE.E. — Fr.  tabular  or  filamentous; 
vittae  straight  (not  arched). 

53.  Striatella. — Fr.  compound,  stalked   at   one   angle; 
vittae  longitudinal  and  continuous  ;  v.  elliptic-lanceolate, 
not  striated  ;  marine. 

54.  Rhabdonema. — Fr.  as   Striatella,  but    vittae    inter- 
rupted ;  v.  with  transverse  granular  striae ;  marine. 

55.  Tetracydus. — Fr.  compound,  filamentous ;  vittae  al- 
ternate, interrupted ;  v.  inflated  at  the  middle ;  striae  trans- 
verse, continuous  ;  aquatic. 

56.  Tabellaria. — Fr.  united  into  a  filament,  subsequently 
breaking  up  into  a  zigzag  chain  ;  vittae  interrupted,  alter- 
nate ;  v.  inflated  at  middle  and  ends ;  aquatic. 

57.  Pleurodesmium. — Fr.  tabular,  united  into  a  filament, 
and  with  a  transverse  median  hyaline  band ;  marine. 

58.  Hyatosira. — Fr.  tabular,  fixed  by  a  stalk   at  one 
angle  ;  vittae  alternate,  interrupted,  bifurcate  at  the  end  ; 
marine. 

59.  Anaulus. — Fr.  rectangular,  single,  compressed,  with 
lateral  inflections,  giving  the  valves  a  ladder-like  appear- 
ance ;  marine. 

60.  Biblarium. — Fr.  as  Tetracydus,  but  single  ;  fossil. 

61.  Terpsinoe. — Fr.  tabular,  obsoletely   stalked,  subse- 
quently connected  by  isthmi ;  vittae  transverse,  short,  in- 
terrupted, and  capitate  ;  aquatic  and  marine. 

62.  Stylobiblium. — Fr.  compound ;  v.  circular,  sculptured 
with  continuous  striae  ;  fossil. 


ft  With  a  Median  apparent  (pseudo)  Nodule. 
63.  Grammatophora. — Fr.  at  first   adnate,  afterwards 


148  THE    MICROSCOPIST. 

forming  a  zigzag  chain ;  vittse  two,  longitudinal,  inter- 
rupted, and  more  or  less  figured  ;  marine. 

TRIBE  III.  AREOLATJE.— Valves  circular,  with  cell-like 
(areolar)  markings,  visible  by  ordinary  illumination. 

SUB-TRIBE  1.  DISCIFORMES. — Valves  alike,  without  ap- 
pendages or  processes. 

COHORT  14.  COSCINODISCE^:. — Valves  circular. 

64.  Actinocydus. — Fr.   solitary;    v.  circular,  undulate, 
the  raised  portions  like  rays  or  hands  radiating  from  the 
centre,  which  is  free  from  markings  ;  marine  and  fossil. 

65.  Actinoptychus. — Fr.  as  Actinocydus,  but   radiating 
internal  septse,  as  well  as  rays. 

66.  Costinodiscus . — Fr.  single ;   v.  circular,  areolar  all 
over ;  marine  and  fossil. 

67.  Arachnoidiscus.—Fr.  single ;  v.  circular,  not  undu- 
late, with  concentric  and  radiating  lines,  and  intermediate 
areola  absent  from  the  centre  (pseudo-nodule) ;   marine 
and  fossil. 

68.  Asterolampra. — Fr.  single;  v.  circular, finely  areolar, 
except  in  the  centre  and  at  equidistant  clear  marginal  rays 
radiating  from  the  centre,  which  is  traversed  by  radiating 
dark  lines  (>septa),  alternating  with  the  marginal  rays  ; 
fossil. 

69.  Aster  omphalos. — As  Asterolampra,  but  two  of  the 
central  dark  lines  parallel,  and  the  corresponding  mar- 
ginal ray  obliterated ;  fossil. 

70.  Halionyx. — Fr.  single ;  v.  circular,  without  septa, 
with  rays  not  reaching  the  centre,  and  with  intermediate 
shorter  rays ;  between  the  rays  transverse  areolar  lines ; 
fossil. 

71.  Odontodiscus. — Fr.    single,   lenticular ;    v.   covered 
with  puncta  (areolee),  arranged  in  radiating  rows  on  ex- 
centrically  curved  lines,  and  with  erect  marginal  teeth  ; 
fossil. 

72.  Omphalopelta. — As  Actinoptychus,  but  upper  part  of 
margin  of  valves  with  a  few  erect  spines  ;  fossil. 


THE    MICROSCOPE    IN    HISTOLOGY    AND    BOTANY.       149 

73.  Symbdoph&ra. — Fr.  single,  disk-shaped  ;  v.  with  in- 
complete septa  radiating  from  the  solid  angular  umbili- 
cus, and  intermediate  bundles  of  radiating  lines ;  marine 
and  fossil. 

74.  Systephania. — Fr.  single ;  v.  circular,  areolar,  with- 
out rays  or  septa,  with  a  crown  of  'spines  or  an  erect 
membrane  on  the  outer  surface  of  each  valve ;  fossil. 

COHORT  15.  ANGULIFERA. — Valves  angular. 

75.  Amphitetras. — Fr.  at  first  united,  afterwards  sepa- 
rating into  a  zigzag  chain,  rectangular;  v.  rectangular, 
the  angles  often  produced  ;  marine. 

76.  Amphipentms. — Fr.  solitary ;  v.  pentangular ;  fossil. 

77.  Lithodesmium. — Fr.  united  into  a  straight  filament ; 
v.  triangular,  one  side  plane,  the  others  undulate ;  marine. 


TRIBE  IY.  APPENDICULAT^E. — Valves  with  processes  or 
appendages,  or  with  the  angles  produced  or  inflated. 
COHORT  16.  EUPODISCE^E. — Fr.  disk-shaped;  v.  circular. 

78.  Eupodiscus. — Fr.  single,  disk-shaped ;   v.  circular, 
with  tubular  or  horn-like  processes  on  the  surface ;  aquatic 
and  marine. 

79.  Auliscus. — As  Eupodiscus,  but  processes  obtuse  and 
more  solid ;  fossil. 

80.  Insilella. — Fr.   single,  fusiform ;   v.  equal,  with   a 
median  turgid  ring  between  them  ;  marine. 

COHORT  17.  BIDDULPHIE.E. — Fr.  flattened;  v.  elliptical 
or  suborbicular. 

81.  Biddulphia. — Fr.  rectangular,  more  or  less  united 
into  a  continuous  or  zigzag  filament;  the  angles  inflated 
or  produced  into  horns  ;  v.  convex,  centre  usually  spinous  ; 
marine. 

82.  Isthmia. — Fr.  rhomboidal  or  trapezoidal,  cohering 
by  one  angle ;  angles  produced ;  marine. 

83.  Chcetoceros. — Fr.  compressed ;  v.  equal,  with  a  long 
spine  or  filament  on  each  side ;  marine. 


150  THE    MICROSCOPIST. 

84.  Rhizoselenia. — Fr.  elongate,  subcylindrical,  marked 
with  transverse  or  spiral  lines,  ends  oblique  or  conical, 
and  with  one  or  more  terminal  bristles ;  marine. 

85.  Hemiaulus. — Fr.   single,   compressed,  rectangular; 
angles  produced  into  tubular  direct  processes,  those  on 
one  valve  longer  than  on  the  other  ;  fossil. 

86.  Syringidium. — Fr.  single,  terete,  acuminate  at  one 
end,  two-horned  at  the  other  ;  marine. 

87.  Periptera. — Fr.  single,  compressed  ;  v.  unequal,  one 
simply  turgid,  the  other  with  marginal  wings  or  spines ; 
fossil. 

88.  Dicladia. — Fr.  single;  v.  unequal,  one  turgid  and 
simple,  the  other  two-horned  ;  fossil. 

COHORT  18.  ANGULAT^E. — Valves  angular. 

89.  Triceratium. — Fr.  free ;   v.  triangular,  each  angle 
with  a  minute  tooth  or  horn  ;  marine. 

90.  Syndendrium. — Fr.  single,  subquadrangular ;  v.  un- 
equal, slightly  turgid,  one  smooth,  the  other  with  numer- 
ous median  spines,  or  little  horns  branched  at  the  ends. 


B.  Frustules  enveloped  in  a  mass  of  Gelatin,  or  contained  in 
Gelatinous  Tubes,  forming  a  Frond. 

91.  Mastogloia. — Frond  mammilate ;  fr.  like  Navicula, 
but  hoops  with  loculi ;  aquatic  and  marine. 

92.  Dickieia. — Frond    leaf-like ;    fr.  like  Navicula    or 
Stamoneis  ;  marine. 

93.  Berkeleya. — Frond  rounded  at  base,  filamentous  at 
circumference  ;  fr.  navicular ;  marine. 

94.  Homoeocladia. — Frond  sparingly  divided,  filiform ; 
fr.  like  Nitzschia  ;  marine. 

95.  Colletonema.  —  Frond    filamentous,   filaments    not 
branched  ;  fr.  like  Navicula  or  Gyrosigma  ;  aquatic. 

96.  Schizonema. — Frond  filamentous,  branched ;  fr.  like 
Navicula';  marine. 


THE    MICROSCOPE    IN    HISTOLOGY    AND    BOTANY.      151 

97.  Encyonema. — Frond  filamentous,  but  little  branched  ; 
fr.  like  Cymbella ;  aquatic. 

98.  Syncydia. — Fr.  those  of  Gymbella,  united  in  circular 
bands,  immersed  in  an  amorphous  gelatinous  frond ;  ma- 
rine. 

99.  Frustulia. — Fr.  as  Navicula,  irregularly  scattered 
through  an  amorphous  gelatinous  mass  ;  aquatic. 

100.  Micromega. — Fr.  as  Navicula,  arranged  in  rows  in 
gelatinous  tubes,  or  surrounded  by  fibres,  these  being  in- 
closed in  a  filiform  branched  frond  ;  marine. 

The  family  of  Nostochince  is  allied  to  the  PalmellacecK. 
It  consists  of  beaded  filaments  suspended  in  a  gelatinous 
frond.  The  gelatinous  masses  of  Nostoc  often  appear  quite 
suddenly  in  damp  places,  and  have  been  called  "fallen 
stars."  They  attracted  the  notice  of  the  alchemists,  and 
enter  into  many  of  their  recipes  for  the  transmutation  of 
metals.  What  have  been  termed  showers  of  flesh  or  of 
blood,  originated  in  all  probability  in  the  rapid  develop- 
ment of  similar  masses.  Many  botanists  regard  them  as 
the  "  gonidia  "  of  Collema  and  other  lichens. 

The  Oscillatoria,  so  called  from  the  singular  oscillatory 
motion  of  their  filaments,  consist  also  of  cells  which  mul- 
tiply in  a  longitudinal  direction  by  self-division.  The 
Ulvacece,  to  which  the  grass-green  sea-weeds  belong,  in- 
crease in  breadth  as  well  as  length  by  the  subdivision  of 
cells,  so  as  to  produce  a  leaf-like  expansion  (Plate  X,  Fig. 
112).  An  illustration  of  the  simpler  forms  of  reproduction 
in  Protophytes  is  seen  in  Zygnema,  so  called  from  the  sin- 
gular manner  in  which  the  filaments  are  yoked  together 
in  pairs.  In  an  early  stage  of  growth,  while  multiplica- 
tion of  cells  proceeds  by  subdivision,  the  endochrome  is 
generally  diffused,  but  about  the  time  of  conjugation  it 
arranges  itself  usually  into  a  spiral.  Adjacent  cells  put 
forth  protuberances,  which  unite  and  form  a  free  passage 
between  them,  and  the  endochrome  of  one  cell  passes  over 


152  THE    MICROSCOPIST. 

into  the  other  and  forms  the  spore.  In  Sphoeroplea  the 
endochrome  of  the  "  oospore  "  breaks  up  into  segments, 
which  escape  as  "  microgonidia."  Each  of  these  have 
two  vibratile  filaments,  which  elongate  so  as  to  become 
fusiform,  and  at  the  same  time  change  from  red  to  green. 
Losing  their  motile  power  they  become  filaments,  in  which 
the  endochrome,  by  the  multiplication  of  vacuoles,  be- 
comes frothy.  After  a  time  the  particles  of  endochrome 
assume  a  globular  or  ovoid  shape,  and  openings  occur  in 
the  cell- wall.  In  other  filaments  the  endochrome  is  con- 
verted into  antherozoids,  each  of  which  is  furnished  with 
two  filaments,  by  means  of  which  they  swim  about  and 
enter  the  openings  of  the  spore-cells,  in  which  they  seem 
to  dissolve  away.  The  contents  of  the  spore-cell  then 
becomes  invested  with  a  membranous  envelope ;  the  color 
changes  from  green  to  red  ;  a  second  investment  is  formed 
within  the  first,  which  extends  itself  into  stellate  projec- 
tions. "When  set  free  the  mass  is  a  true  oospore,  and 
ready  to  repeat  the  process  above  described.  In  (Edogo- 
nium  the  antherozoids  are  developed  in  a  body  called  an 
"  androspore,"  which  is  set  free  from  a  germ-cell,  and 
which  being  furnished  with  cilia  resembles  an  ordinary 
zoospore.  This  androspore  attaches  itself  to  the  outer 
surface  of  a  germ-cell,  a  sort  of  lid  drops  from  its  free 
extremity,  which  sets  free  its  contained  antherozoids. 
These  enter  an  aperture  formed  in  the  cell-wall  of  the 
oospore,  and  fertilize  the  contained  mass  by  blending 
with  it. 

Examination  of  the  Higher  Cryptogamia. — It  would  en- 
large this  volume  far  beyond  its  proposed  limits  to  refer 
to  the  particular  instances  of  form  or  function  which  the 
microscope  reveals  to  the  systematic  botanist  or  physiolo- 
gist, nor  is  this  necessary,  since  well-written  treatises  on 
structural  botany  are  quite  available.  We  content  our- 
selves, therefore,  in  the  remainder  of  this  chapter,  with 
pointing  out  the  methods  of  examination  by  which  the 


THE    MICROSCOPE    IN    HISTOLOGY    AND    BOTANY.      153 

views  of  other  observers  may  be  verified,  or  additions 
made  to  our  knowledge  of  vegetable  life. 

The  lower  forms  of  algae  and  fungi,  to  which  we  have 
already  referred,  need  scarcely  any  preparation,  save  the 
disentanglement  of  twisted  threads  under  the  simple  mi- 
croscope, or  a  gentle  teasing  with  needles,  or  rinsing  with 
water.  The  solution  of  iodine,  and  of  iodine  and  sulphuric 
acid,  will  suffice  to  exhibit  the  nature  of  the  cell-wall  and 
cell-contents.  In  more  highly  developed  plants  it  will  be 
necessary  to  take  thin  sections  from  different  parts,  and 
in  different  but  definite  directions.  These  sections  may 
be  made  by  hand,  or  between  pieces  of  pith  or  cork  by 
means  of  a  section-cutter.  In  some  instances  some  of  the 
methods  of  staining  will  also  be  useful.  Dr.  Hunt,  of 
Philadelphia,  has  proposed  a  plan  of  staining  which  is 
well  adapted  to  all  vegetable  tissues.  He  first  soaks  the 
part  or  section  in  strong  alcohol  to  dissolve  the  chloro- 
phyll, then  bleaches  it  in  a  solution  of  chlorinated  soda. 
It  is  then  placed  in  a  solution  of  alum,  and  afterwards  in 
one  of  extract  of  logwood.  By  transferring  it  to  weak 
alcohol  and  afterwards  to  stronger,  it  is  deprived  of  its 
water,  and  after  being  made  transparent  with  oil  of  cloves, 
it  is  ready  for  mounting  in  balsam  or  dammar  varnish. 
Care  must  be  taken  to  wash  it  well  after  each  of  the 
preliminary  steps  before  staining. 

In  the  higher  algre,  the  layers  of  cells  assume  various 
sizes  and  shapes,  and  the  nature  of  their  fructification  is 
of  great  interest.  Sections  may  be  made  of  the  "  recep- 
tacles "  at  the  extremities  of  the  fronds,  which  contain 
filaments,  whose  contents  become  antherozoids.  The  pear- 
shaped  sporangia  in  the  receptacles  subdivide  into  clusters 
of  eight  cells,  called  octospores,  which  are  liberated  from 
their  envelopes  before  fertilization. 

The  red  sea-weeds,  or  RhodospermecB,  afford  many  beau- 
tiful forms  for  the  microscope.  The  "  tetraspores  "  are 
imbedded  in  the  fronds. 


154  THE    MICROSCOPIST. 

In  lichens,  the  apotkecia  form  projections  from  the  thal- 
lus,  or  general  expansion  produced  by  cell-division.  A 
vertical  section  shows  them  to  contain  asci  or  spore-cases 
amid  straight  filaments,  or  elongated  cells  called  para- 
physes. 

The  fronds  of  Hepatica  or  liverworts  bear  stalks  with 
shield-like  disks,  which  carry  autheridia,  and  others  with 
radiating  bodies  bearing  archegonia,  which  afterwards 
give  place  to  the  sporangia  or  spore-cases.  The  spores 
are  associated  with  elaters,  or  elastic  spiral  fibres,  which 
suddenly  extend  themselves  and  disperse  the  spores. 

The  Characece  are  often  incrusted  with  carbonate  of 
lime,  which  may  be  removed  with  dilute  sulphuric  acid. 
The  motion  of  the  bioplasm  in  the  cells  of  the  stem  is 
often  well  seen.  The  cells  in  which  the  spiral  filaments 
or  antheridia  are  developed,  are  strung  together  like  a 
row  of  pearls.  The  position  and  construction  of  the  spores 
also  should  be  examined,  as  well  as  the  mode  of  growth 
in  the  plant  by  division  of  the  terminal  cell  (Plate  XI, 
Fig.  113). 

Stems  of  mosses  and  liverworts  should  be  examined  by 
means  of  transverse  and  longitudinal  sections.  Similar 
sections  through  the  half-ripe  fruit  of  a  moss  will  show 
the  construction  of  the  fruit,  the  peristome,  the  calyptra, 
etc.  The  ripe  spores  may  be  variously  examined  dry,  in 
water,  in  oil  of  lemons,  and  in  strong  sulphuric  acid.  The 
capsules  or  urns  of  mosses  are  not  now  regarded  as  their 
fructification,  but  its  product. 

The  true  antheridia  and  pistillidia  are  found  among  the 
bases  of  the  leaves,  close  to  the  axis.  The  fertilized  "  em- 
bryo-cell "  becomes  gradually  developed  by  cell-division 
into  a  conical  body  or  spore-capsule,  elevated  on  a  stalk. 
The  peristome,  or  toothed  fringe,  seen  around  the  mouth 
of  the  urn  when  the  calyptra  or  hood,  and  operculum  or 
lid,  are  removed,  furnishes  a  beautiful  object  for  the  bi- 
nocular microscope. 


PLATE  XI 

FIG. 113. 


Antheridia  of  Chara  fragilis : — A,  antheridium  or  "globule"  developed  at  the  base  of  pistillidium  or 
"  nucule  ;"  B,  nucule  enlarged,  globule  laid  open  by  the  separation  of  its  valves;  c,  one  of  the  valves, 
with  its  group  of  antheridial  filaments,  each  composed  of  a  linear  series  of  cells,  within  every  one  of 
which  an  antherozoid  is  formed  ;  in  D,  E,  and  F,  the  successive  stages  of  this  formation  are  seen ;  and  at 
G  is  shown  the  escape  of  the  mature  antherozoids,  H.  (From  Carpenter.) 


Development  of  Prothalium  of  Pteris  serrulata : — A,  spore  set  free  from  the  theca;  B,  spore  beginning 
to  germinate,  putting  forth  the  tubular  prolongation  a,  from  the  principal  cell  b;  r,  first  formed  linear 
series  of  cells ;  D,  prothallium  taking  the  form  of  a  leaf-like  expansion ;  a  first  and  6  second  radical 
fibre ;  c,  d,  the  two  lobes,  and  e  the  indentation  between  them  ;  /, /,  first-formed  part  of  the  prothallium  ; 
g,  external  coat  of  the  original  spore  ;  h,  A,  antheridia.  (From  Carpenter.) 


THE    MICROSCOPE    IN    HISTOLOGY    AND    BOTANY.       155 

The  Sphagnum,  or  bog-moss,  has  large  and  elongated 
leaf-cells,  with  loosely-coiled  spiral  fibres,  and  their  mem- 
branous walls  have  large  apertures.  Their  spores  are  of 
two  kinds,  and  when  germinating  in  water,  produce  a  long 
filament  with  root-fibres  at  the  lower  end  and  a  nodule 
at  the  upper,  from  which  the  young  plant  is  formed.  If 
grown  on  wet  peat,  instead  of  a  filament  there  is  evolved 
a  lobed  foliaceous  prothallium,  resembling  the  frond  of 
liverworts. 

In  ferns  the  structure  approximates  to  true  flowering 
plants,  while  the  reproductive  organs  are  those  of  crypto- 
gamia.  Thin  sections  of  the  stem,  cut  obliquely,  show 
the  scalariform  or  ladder-like  vessels.  The  fructification 
is  usually  found  on  the  under  side  of  the  frond  in  isolated 
spots  called  son.  Each  of  these  contains  a  number  of  cap- 
sules or  thecce,  and  each  capsule  is  surrounded  by  an  an- 
nidus  or  ring,  whose  elasticity  opens  the  capsule  when 
ripe  and  permits  the  spores  to  escape.  The  spores  are 
somewhat  angular,  and  when  vegetating  give  rise  to  a 
leaf-like  expansion  called  a  prothallium.  In  this  the  an- 
theridia  and  archegonia,  which  represent  the  true  flower 
of  higher  plants,  are  developed.  The  ciliated  anthero- 
zoids  from  the  antheridia  penetrate  the  cavity  of  the 
archegonium  and  fertilize  the  "  germ-cell,"  which  subdi- 
vides and  becomes  a  young  fern,  while  the  prothallium, 
having  discharged  the  functions  of  a  nurse,  withers  away 
(Plate  XI,  Fig.  114).  The  group  of  EquisetacecR  or  horse- 
tails is  interesting  from  the  siliceous  skeletons  of  the  epi- 
dermis, already  referred  to,  page  131,  as  well  as  for  the 
elastic  filaments  attached  to  their  spores. 

EXAMINATION  OF  HIGHER  PLANTS. 

The  elementary  tissues  described  in  the  beginning  of 
this  chapter  are  chiefly  characteristic  of  phanerogamic 
plants,  yet  some  additional  particulars  remain  to  be  no- 


156  THE    MICROSCOPIST. 

ticed  in  connection  with  the  axis  or  stem,  the  leaves, 
flowers,  and  fruit. 

1.  The  Stem. — The  arrangement  of  fibro-vascular  bun- 
dles, L  e..  woody  fibres  and  ducts,  differs  widely  in  the 
two  botanical  divisions  of  Monocotyledons  and  Dicotyle- 
dons. In  the  first  the  growth  is  endogenous,  and  a  section 
exhibits  the  bundles  of  fibres  and  ducts  disposed  without 
regularity  in  the  mass  of  cellular  tissue  which  forms  the 
basis  of  the  fabric.  In  the  second,  or  exogenous  stems, 
the  fibro-vascular  bundles  are  wedge-shaped,  and  inter- 
posed between  the  bark  and  the  pith,  being  kept  apart  by 
plates  of  cellular  tissue,  called  medullary  rays,  proceeding 
from  the  pith. 

The  course  of  the  vascular  bundles  in  monocotyledons 
should  be  carefully  followed,  either  by  maceration  or 
minute  dissection.  In  the  dicotyledonous  stem,  sections 
must  be  made  in  three  directions,  transversely,  longitu- 
dinally across  the  diameter,  and  at  a  tangent  from  the 
bundles  of  fibres.  The  section-cutter,  described  page  63, 
will  be  serviceable,  although  a  sharp  razor  or  scalpel  may 
serve.  The  size,  form,  and  contents  of  the  pith-cells 
should  be  noticed,  and  their  transition  to  wood-cells. 
The  arrangement  of  the  medullary  rays,  of  the  wood-cells, 
and  of  the  ducts  must  also  be  observed,  and  in  the  Coni- 
ferse  the  position  of  the  pits.  The  cambium  layer,  between 
the  bark  and  wood,  may  have  its  cells  rendered  more 
transparent  by  weak  alkalies,  and  their  contents  tested 
with  iodine  solution.  The  course  and  construction  of 
laticiferous  vessels  in  the  bark,  when  present,  and  of  the 
cork-cells  of  the  tuberous  layer,  may  be  noted. 

Fossil  woods  may  be  cut  with  a  watch-spring  saw,  and 
ground  on  a  hone  like  bone  or  teeth.  Sometimes  it  is 
best  to  break  off  small  lamella  by  careful  strokes  with  a 
steel  hammer.  It  is  sometimes  useful  to  digest  fossil 
wood  in  a  solution  of  carbonate  of  soda  for  several  days 
before  cutting. 


THE    MICROSCOPE    IN    HISTOLOGY    AND    BOTANY.      157 

2.  Leaves. — These  should  be  examined  by  thin  longitu- 
dinal and  transverse  sections.    The  epidermis  of  both  sides 
should  be  detached,  and  the  position  and  arrangement  of 
the  stomata  observed  (Plate  VII,  Fig.  100).     The  hairs 
of  the  epidermis,  the  arrangement  of  the  parenchyma,  and 
the  distribution  of  the  vascular  bundles  in  the  form  of 
nerves,  are  also  of  importance. 

3.  Flowers. — For  ascertaining  the  number  and  position 
of  the  parts  of  the  flower,  transverse  sections  at  different 
heights  through  an  unopened  bud  may  be  taken,  together 
with  a  longitudinal  section  exactly  through  the  middle. 
The  general  structure  of  sepals  and  petals  corresponds  with 
that  of  leaves,  but  there  are  some  peculiarities.     Thus  the 
cells  of  the  petal  of  the  geranium  exhibit  when  deprived 
of  epidermis,  dried  and  mounted  in  balsam,  a  peculiar 
mammillated  appearance  with  radiating  hairs  (Plate  VIII, 
Fig.  102).     Anthers  and  pollen  grains  are  also  interesting 
microscopic  objects.     The  protrusion  of  the  inner  mem- 
brane through  the  exterior  pores  in  pollen  may  be  stimu- 
lated by  moistening  with  water,  dilute  acid,  etc.     The 
penetration  of  the  pollen  tubes  through  the  tissue  of  the 
style  may  be  traced  by  sections  or  careful  dissection.     The 
heartsease,  viola  tricolor,  and  the  black  and  red  currant, 
ribes  nigrum  and  rubrum,  have  been  recommended  for  this 
purpose. 

4.  Seeds. — The   reticulations  or  markings  on  various 
kinds  of  seeds  render  them  frequent  objects  for  observa- 
tion with  the  binocular  microscope.     Adulterations  may 
also  be  detected  in  this  way,  as  well  as  imperfect  seeds  in 
any  sample,  a  subject  of  much  importance  to  the  practical 
farmer. 


153  THE    MICROSCOPIST. 

CHAPTER   XL 

THE   MICROSCOPE   IN   ZOOLOGY. 

WE  have  already  seen  that  both  animal  and  vegetable 
structures  originate  in  a  jelly-like  mass  or  cell,  and  that 
in  the  simple  forms  it  is  difficult,  if  not  impossible,  to 
determine  whether  the  object  is  an  animal  or  a  vegetable. 
The  mode  of  alimentation,  and  not  structure,  is  our  only 
guide  in  the  discrimination  of  the  Protozoa  or  elementary 
animal  forms  from  Protophytes  or  simple  vegetables. 

It  has  been  proposed  by  Professor  Hseckel  to  revive  the 
idea  of  a  kingdom  of  nature  intermediate  between  plants 
and  animals,  but  it  does  not  appear  that  any  gain  to  sci- 
ence would  result  from  such  an  arrangement. 

I.  MONERA. — The  simplest  types  of  Protozoa  are  mere 
particles  of  living  jelly  (Plate  XII,  Fig.  115),  yet  they 
possess  the  power  of  contraction  and  extension,  and  of 
absorbing  alimentary  material  into  their  own  substance 
for  its  nutrition.     The  Bathybius,  from  the  "globigerina 
mud,"  referred  to  on  page  93,  seems  to  have  been  an  in- 
definite expansion  of  such  protoplasm  or  bioplasm. 

II.  RHIZOPODS. — This  term  (meaning  root-footed)  is  ap- 
plied to  such  masses  of  sarcode  or  bioplasm  as  extend  long 
processes,  called  pseudopodia,  as  prehensile  or  locomotive 
organs  (Plate  XII,  Fig.  116).     The  Rhizopods  are  either 
indefinitely  organized  jelly,  like  Monera,  or  attain  a  cov- 
ering or  envelope  of  membrane  called  ectosarc,  while  the 
thin  contents  are  termed  endosarc.     The  first  order  of 
Rhizopods,  Reticularia,  consist  of  indefinite  extensions  of 
freely  branching  and  mutually  coalescing  bioplasm.     The 
second  order,  Radiolaria,  have  rod-like  radiating  exten- 
sions of  the  ectosarc,  which  do  not  coalesce.     The  order 
Lobosa  are  lobose  extensions  of  the  body  itself,  as  in  the 


THE    MICROSCOPE    IN    ZOOLOGY.  159 

Amoeba  princeps  already  described.  Some  of  this  latter 
order,  as  Arcella  and  Diffliigia,  are  testaceous.  In  Arcella 
the  test  is  a  horny  membrane,  analogous  to  the  chitine 
which  hardens  the  integuments  of  insects.  In  Difflugia 
the  test  is  made  up  of  minute  particles  of  gravel,  shell, 
etc.,  cemented  together.  From  the  opening  the  amoeboid 
body  puts  forth  its  pseudopodia  (Plate  XII,  Fig.  117). 
Connected  with  Rhizopods  are  three  remarkable  series  of 
forms,  generally  marine,  and  distinguished  by  skeletons 
of  greater  or  less  density,  which  afford  many  objects  of 
interest  to  the  microscopist.  These  are  the  Foraminifera, 
the  Polycystina,  and  the  Sponges  or  Porifera.  The  shells 
of  the  Foraminifera  are  calcareous,  and  those  of  Polycys- 
tina  siliceous ;  both  are  perforated  with  numerous  aper- 
tures, which  in  Polycystina  are  often  large.  We  have 
previously  referred  to  these  forms  as  occurring  in  a  fossil 
state. 

Some  Foraminifera  have  porcellanous,  and  others  vitre- 
ous or  hyaline  shells,  usually  many-chambered,  and  of  every 
shape  between  rectilinear  and  spinal.  Most  of  them  are 
microscopic,  but  some  are  of  considerable  size,  as  the  Or- 
bitolites,  which  are  found  in  tertiary  limestones  in  Malabar. 
The  Nummulitic  limestone,  which  extends  over  large  areas 
of  both  hemispheres,  and  of  which  the  pyramids  of  Egypt 
are  built,  is  composed  of  the  remains  of  the  genus  Num- 
mulina;  and  the  Eozoon  Canadense  has  been  shown  by 
Drs.  Dawson  and  Carpenter  to  belong  to  the  Foramini- 
feral  type. 

In  some  Foraminifera  the  true  shell  is  replaced  by  a 
sandy  envelope,  whose  particles  are  often  cemented  by 
phosphate  of  iron.  Dr.  Carpenter,  whose  researches  have 
largely  extended  our  knowledge  of  this  group,  pertinently 
remarks  that  "there  is  nothing  more  wonderful  in  nature 
than  the  building  up  of  these  elaborate  and  symmetrical 
structures  by  mere  jelly  specks,  presenting  no  trace  what- 
ever of  that  definite  c  organization '  which  we  are  accus- 


160  THE    MICROSCOPIST. 

tomed  to  regard  as  necessary  to  the  manifestations  of 
conscious  life."* 

The  Polycystina^  like  the  Foraminifera,  are  beautiful 
objects  for  the  binocular  microscope,  with  the  black- 
ground  illumination  by  the  Webster  condenser,  the  spot- 
lens,  or  the  paraboloid. 

The  Porifera  or  sponges  begin  life  as  solitary  Amoeba, 
and  amid  aggregations  formed  by  their  multiplication, 
the  characteristic  spicules  of  sponge-structure  make  their 
appearance.  In  one  group,  the  skeleton  is  a  siliceous 
framework  of  great  beauty.  In  Hyalonema,  the  silica  is 
in  bundles  of  long  threads  like  spun  glass.  Sometimes 
sponge  spicules  are  needle-like,  straight  or  curved,  pointed 
at  one  or  both  ends ;  sometimes  with  a  head  like  a  pin, 
furnished  with  hooks,  or  variously  stellate.  Dr.  Carpen- 
ter thinks  it  probable  that  each  spicule  was  originally  a 
segment  of  sarcode,  which  has  undergone  either  calcifica- 
tion or  silicification  (Plate  XII,  Fig.  118). 

III.  INFUSORIAL  ANIMALCULES. — From  the  earliest  his- 
tory of  the  microscope,  the  minute  animals  found  in  vari- 
ous infusions  or  in  stagnant  pools,  etc.,  have  attracted 
attention.  We  owe  to  Professor  Ehrenberg  the  first  sci- 
entific arrangement  of  this  class,  and  although  more  ex- 
tended observations  have  changed  his  classification,  yet 
many  of  his  views  are  still  accepted  by  the  most  recent 
investigators.  Ehrenberg  divided  this  class  into  two 
groups,  which  represent  very  different  grades  of  organi- 
zation. The  first  he  called  Polygastrica  (many-stomached) 
from  a  view  of  their  structure,  which  subsequent  examin- 
ations have  not  confirmed.  The  other  group  is  that  of 
Rotifera  or  Rotatoria,  a  form  of  animal  life  which  is  most 
appropriately  classed  among  worms.  The  term  Infusoria 
is  now  applied  to  those  forms  which  Professor  Ehrenberg 

*  The  Microscope  and  its  Revelations,  by  W.  B.  Carpenter,  M.D., 
LL.D.,  etc. 


Monera  (Amoeba}. 


PLATE  Xll. 


A,  Dijflugiaproteiformis;  B,Difflugiaoblonga;  c,Arcella 
acuminata;  D,  Ar cello,  dentata. 


Gromia oviformis, with  its  pseudopodia  extended. 


FIG.  118. 


Structure  of  Grantia  compressa:  B,  small  portion  highly  magnified. 


THE    MICROSCOPE    IN    ZOOLOGY.  161 

% 

called  poly  gastric  animalcules.  Yet  a  large  section  de- 
scribed by  him  in  this  connection,  including  the  Desmidi- 
acece,  Diatomacece,  Volvocinece,  and  other  protophytes,  have 
been  transferred  by  naturalists  to  the  vegetable  kingdom. 

The  bodies  of  the  Infusoria  consist  of  sarcode  or  bio- 
plasm, having  an  outer  layer  of  firmer  consistence.  Some- 
times the  integument  is  hardened  on  one  side  so  as  to  form 
a  shield,  and  in  other  cases  it  is  so  prolonged  and  doubled 
upon  itself  as  to  form  a  sheath  or  cell,  within  which  the 
animalcule  lies.  The  form  of  the  body  is  more  definite 
than  that  of  Amoeba,  so  as  to  be  characteristic  of  species. 
It  may  be  oblong,  oval,  or  round ;  and  some  kinds,  as 
Vorticella,  are  attached  to  a  footstalk,  which  has  the  power 
of  contracting  in  a  spiral  coil.  No  distinct  muscular 
structure  can  be  detected  in  the  Infusoria,  yet  the  general 
substance  of  the  body  is  contractile.  In  most  species 
short  hair-like  filaments  or  cilia  project  from  the  surface, 
sometimes  arranged  in  one  or  more  rows  round  the  mouth, 
and  moving  to  all  appearance  under  the  influence  of  voli- 
tion. In  others  there  are  one  or  two  flagelliform  filaments, 
or  long  anterior  cilia  with  vibratile  ends.  Others,  again, 
have  setse  or  bristles,  which  assist  in  locomotion.  The 
motions  of  some  are  slow,  and  of  others  quite  rapid. 

The  interior  of  the  sarcode  body  exhibit  certain  round- 
ish spots,  sometimes  containing  Diatoms  or  other  foreign 
substances.  They  have  been  called  gastric  vesicles,  cells, 
spaces,  or  sacculi.  They  are  only  visible  from  their  con- 
tents, and  seem  to  be  mere  spaces  without  a  living  mem- 
brane. If  a  little  indigo  or  carmine  is  diffused  in  the 
water  which  contains  the  Infusoria,  the  cavities  will  soon 
be  filled  and  become  distinct.  If  watched  carefully  they 
will  appear  to  move  round  the  body  of  the  animal,  and  as 
the  pigment  escapes  at  some  part  of  the  surface,  the  spots 
will  disappear.  Ehrenberg  regarded  these  spots  as  so 
many  stomachs  arranged  about  a  common  duct,  but  the 
common  opinion  at  present  regards  them  as  temporary 

11 


162  THE    MICROSCOPIST. 

I 

digestive  sacs  made  by  the  inclosure  of  food  by  the  soft 
bioplasm. 

In  addition  to  the  "vacuoles"  described,  contractile 
vesicles  are  seen  which  contract  and  dilate  rhythmically, 
and  do  not  change  their  position.  They  have  been  con- 
sidered to  serve  for  respiration. 

Most  of  the  Infusoria  multiply  by  self-division  (Plate 
XIII,  Fig.  119),  and  at  certain  times  undergo  an  encyst- 
ing process,  much  resembling  the  "still"  condition  of  Pro- 
tophytes,  and  like  that  serving  for  preservation  under 
circumstances  which  are  unfavorable  to  ordinary  vital 
activity.  The  gemmules  or  progeny  which  result  from 
the  bursting  of  the  cyst  do  not  always  resemble  the  parent 
in  form.  The  recent  researches  of  Drs.  Dallinger  and 
Drysdale  have  shown  considerable  variety  in  the  life  his- 
tory of  the  Infusoria.  In  some  instances  the  product  of 
the  encysting  process  was  not  a  mass  of  granules,  but  an 
aggregation  of  minute  germinal  particles  not  more  than 
sWaooth  of  an  inch  in  diameter,  and  capable  of  resisting 
heat,  either  by  boiling  or  by  dry  heating  up  to  300°  F. 

The  observations  of  M.  Balbiani  show  that  in  many  of 
the  Infusoria,  male  and  female  organs  are  combined  in 
the  same  individual,  but  that  a  congress  of  two  is  neces- 
sary for  the  impregnation  of  the  ova,  those  of  each  being 
fertilized  by  the  spermatozoa  of  the  other. 

There  is  also  a  curious  tribe  of  suctorial  animalcules 
called  Acinetce,  which  put  forth  tubular  prolongations 
which  penetrate  the  bodies  of  other  species  and  grow  in 
their  interior  as  parasites. 

The  systematic  arrangement  of  the  Infusoria  is  yet 
unsettled.  Ehrenberg's  families,  excluding  those  now 
placed  among  Algre  or  Rhizopods,  are  as  follows : 


THE  MICROSCOPE  IN  ZOOLOGY.          163 

A.  Intestinal  tube  absent. 

Body  variable,  without  cilia. 

Carapace  absent,  .....     ASTASI.EA. 

Carapace  present, DINOBRYINA. 

Cilia  or  setae  present. 

Carapace  absent,  .....     CYCLIDINA. 

Carapace  present,  .....     PERIDIN^A. 

B.  Intestinal  tube  present. 

Orifice  single. 

Carapace  absent,    .....     YORTICELLINA. 

Carapace  present, OPHRYDINA. 

Two  opposite  orifices. 

Carapace  absent,     .....     ENCHELIA. 
Carapace  present,  .....     COLKPINA. 
Orifices  differently  placed. 
Carapace  none. 

No  tail,  but  a  proboscis,          .         .     TRACHELINA. 
Tail  present,  mouth  anterior,          .     OPHRYOCERCINA. 
Carapace  present,  .....     ASPIDISCINA. 
Orifices  ventral. 

Carapace  absent. 

Motion  by  cilia,       .         .        .         .     COLPODEA. 
Motion  by  organs,  .         .         .         .     OXYTRICHINA. 
Carapace  present,  .....     EUPLOTA. 


IV.  ROTATORIA  OR  WHEEL  ANIMALCULES. — These  are 
microscopic,  aquatic,  transparent  animals,  of  a  higher 
organization  than  the  Infusoria, -and  belonging  in  all 
probability  to  the  class  Vermes.  Their  chief  interest  to 
the  microscopist  is  derived  from  the  possession  of  a  more 
or  less  lobed,  retractile  disk,  covered  with  cilia,  which, 
when  in  motion,  resemble  revolving  wheels.  They  have 
also  a  complicated  dental  apparatus,  and  generally  a  dis- 
tinct alimentary  canal,  and  are  reproduced  by  ova.  Some 
are  more  or  leos  covered  by  a  carapace,  and  in  most  there 
is  a  retractile  tail-like  foot,  sometimes  terminated  by  a 
suctorial  disk  or  a  pair  of  claw-like  processes.  The  ner- 
vous and  vascular  systems  are  not  well  known,  although 
traces  of  them  are  seen.  The  young  of  some  possess  an 
eye  which  often  disappears  in  the  adult.  They  are  re- 


164  THE    MICROSCOPIST. 

markably  tenacious  of  life,  having  in  some  instances  re- 
vived after  having  been  kept  dry  for  several  years. 

M.  Dujardin  divides  the  Rotifera  into  four  groups  or 
natural  families : 

1.  Those  attached  by  the  foot,  which  is  prolonged  into 
a  pedicle.     It  includes  two  families,  the  Floscularians  and 
the  Melicertians,  in  the  first  of  which  the  sheath  or  cara- 
pace is  transparent,  and  in  the  other  composed  of  little 
rounded  pellets  (Plate  XIII,  Fig.  120). 

2.  The  common  Rotifer  and  its  allies,  which  swim  freely 
or  attach  themselves  by  the  foot  at  will  (Plate  XIII,  Fig. 
121). 

3.  Those  which  are  seldom  or  never  attached,  the  Bra- 
chionians  and  the  Furcularians.     The  former  are  short, 
broad,  and  flat,  and  inclosed  in  a  sort  of  cuirass ;  the  latter 
are  named  from  a  bifurcated,  forcep-like  foot  (Plate  XIV, 
Fig.  122). 

4.  The  Tardigrada  or   water  bears.     These   have   no 
ciliated  lobes,  but  are  in  other  respects  like  their  allies, 
and  seem  to  be  a  connecting  link  between  the  Rotifers 
and  worms.     The  segments  of  the  body,  except  the  head, 
bear  two  fleshy  protuberances  furnished  with  four  curved 
hooks.* 

Y.  POLYPS. — The  animals  of  this  class  were  formerly 
called  Zoophytes,  or  animal  flowers.  They  are  the  most 
important  of  coral-making  animals,  although  the  Hydroids 
and  Bryozoa,  together  with  some  Algse,  as  the  Xullipores, 
share  with  them  the  formation  of  coral,  which  is  a  secre- 
tion of  calcareous  matter.  Dana's  work  on  corals  gives  a 
classification,  of  which  we  present  a  summary. 

A  good  idea  of  a  polyp  may  be  had  from  comparison 
with  the  garden  aster,  the  most  common  form  of  a  polyp 
flower  being  a  disk  fringed  with  petal-like  organs  called 
tentacles. 

The  internal  structure,  like  the  external,  is  radiate,  and 

*  Carpenter  on  the  Microscope. 


PLATE  XIII. 


FIG. 119. 


Fissiparous  multiplication  of  Chilodon  cucullulus. 


FIG.  120. 


FIG.  121. 


Rodifer  vulgaris,  as  seen  at  A,  with 
the  wheels  drawn  in,  and  at  B  with 
the  wheels  expanded;  a,  mouth;  b, 
eye-spots;  c,  wheels;  d,  calcar  (an- 
tenna?); e,  jaws  and  teeth;  /,  ali- 
mentary canal ;  g,  glandular  (?)  mass 
enclosing  it ;  h,  longitudinal  mus- 
cles ;  i,  i,  tubes  of  water  vascular 
system;  k,  young  animal;  Z,  cloaca. 


Slephanoceros  Eichorn it. 


THE  MICROSCOPE  IN  ZOOLOGY.          165 

the  cavity  of  the  body  is  divided  by  septa  into  narrow 
compartments.  The  walls  contain  circular  and  longitu- 
dinal muscles,  which  serve  for  contraction  of  the  body, 
which  is  afterwards  expanded  by  an  injection  or  absorp- 
tion of  water  by  the  mouth. 

The  most  interesting  part  of  the  structure  of  these 
animals,  to  the  microscopist,  is  the  multitude  of  lasso-cells, 
called  also  nettling -cells,  thread  capsules,  and  cnidce,  which 
stud  the  tentacles  and  other  parts  of  the  body,  and  by 
means  of  which  the  prey  of  the  polyp  is  at  once  pierced 
and  poisoned.  A  small  piece  of  the  tentacle  of  a  sea 
anemone  placed  in  a  compressorium  under  the  microscdpe, 
and  subjected  to  gentle  pressure,  will  show  the  protrusion 
of  many  little  dart-like  processes  attached  to  thread-like 
filaments.  Many  observations  indicate  the  injection  of  a 
poison  through  these  darts,  which  is  instantly  fatal  to 
small  animals  (Plate  XIV,  Fig.  123). 

The  polyp  has  no  circulating  fluid  but  the  results  of 
digestion  mixed  with  salt  water,  no  bloodvessels  but  the 
vacuities  among  the  tissues,  and  no  passage  for  excrements 
except  the  mouth  and  the  pores  of  the  body.  Reproduc- 
tion is  both  by  ova  and  by  buds. 

I.  Actinoid  polyps  are  related  to  the  Actinea  or  sea 
anemone.     The  number  of  tentacles  and  interior  septa 
is  a  multiple  of  six. 

II.  Cyathophylloid  polyps  have  the  number  of  tentacles 
and  septa  a  multiple  of  four. 

III.  Alcyonoid  polyps  have  eight  fringed  tentacles.    The 
Alcyonium  tribe  are  among  the  most  beautiful  of  coral 
shrubs.     The  Gorgonia  tribe  has  reticulated  species  like 
the  sea  fan,  and  bears  minute  calcareous  spicules,  often 
brilliantly  colored.     The  Pennatula  tribe  is  unattached, 
and  often  rod-like,  with  the  polyps  variously  arranged. 

VI.  HYDROIDS. — The  type  of  this  class  is  the  common 
Hydra,  which  is  often  found  attached  to  leaves  or  stems 
of  aquatic  plants,  etc.  It  is  seldom  over  half  an  inch  long. 


166  THE    MICROSCOPIST. 

It  has  the  form  of  a  polyp,  with  long  slender  tentacles. 
Besides  these  tentacles  with  their  lasso-cells,  it  has  no 
special  organs  except  a  mouth  and  tubular  stomach.  Like 
the  fabled  Hydra,  if  its  head  be  cut  off  another  will  grow 
out,  and  each  fragment  will  in  a  short  time  become  a  per- 
fect animal,  supplying  whatever  is  wanting,  hence  its  name 
(Plate  XIV,  Fig.  124).  The  Hydra  has  the  power  of  lo- 
comotion, bending  over  and  attaching  its  head  until  the 
tail  is  brought  forward,  somewhat  after  the  manner  of  a 
leech. 

Compound  Hydroids  may  be  likened  to  a  Hydra  whose 
buds  remain  attached  and  develop  other  buds  until  an 
arborescent  structure,  called  a  polypary,  is  produced.  The 
stem  and  branches  consist  of  fleshy  tubes  with  two  layers, 
the  inner  one  having  nutritive  functions,  and  the  outer 
secreting  a  hard,  calcareous,  or  horny  layer.  The  indi- 
viduals of  the  colony  are  of  two  kinds,  the  polypite  or 
nutritive  zooid,  resembling  the  Hydra,  and  the  gonozooid, 
or  sexual  zooid,  developed  at  certain  seasons  in  buds  of 
particular  shape. 

To  mount  compound  Hydrozoa,  or  similar  structures, 
place  the  specimen  alive  in  a  cell,  and  add  alcohol  drop 
by  drop  to  the  sea-water ;  this  will  cause  the  animals  to 
protrude  and  render  their  tentacles  rigid.  Then  replace 
the  alcohol  with  Goadby's  solution,  dilute  glycerin,  or 
other  preserving  fluid.  * 

VII.  ACALEPHS,  or  sea-nettles,  are  of  all  sizes,  from  an 
almost  invisible  speck  to  a  yard  in  diameter.  They  swarm 
in  almost  every  sea,  and  are  frequently  cast  upon  the 
beach  by  the  waves.  They  are  transparent,  floating  free, 
discoid  or  spheroid,  often  shaped  like  a  mushroom  or  um- 
brella, and  their  organs  are  arranged  radiately  round  an 
axis  occupied  by  the  pedicle  or  stalk.  They  are  furnished 
with  muscular,  digestive,  vascular,  and  nervous  systems. 
They  were  formerly  divided  into 

1.  Pulvnonigrada,  from  their  movements  being  eifected 


PLATE  XIV. 

FIG.  122. 


Noteus  quadricornis  :—A,  dorsal  view ;  B,  side  view. 


FIG.  123. 


FIG. 124. 


Hydra  fusca  in  gemmation. 


Filiferous  capsules  of  Helianthoid  Polypes :— A,B, 
Corynactis  Allmanni;  c,  E,  F,  Caryophyllia  Smithii, 
D,  G,  A ctinia  crass icornis ;  H,  Actinia  Candida. 


THE  MICROSCOPE  IN  ZOOLOGY.         167 

by  a  rhythmical  contraction  and  dilation,  as  in  Rhizistoma, 
etc.  2.  Cilograda,  moving  by  narrow  bands  of  vibratile 
cilia  variously  disposed  over  the  body.  In  Beroe  the  cilia 
are  transformed  into  flat  fin-like  shutters,  arranged  in 
eight  longitudinal  bands.  InVenns's  girdle,  Cestum  Ve- 
neris,  the  margins  of  a  gelatinous  ribbon  are  fringed  with 
cilia.  3.  Physograda,  which  move  by  means  of  an  expan- 
sile bladder,  as  the  Physalia^  or  Portuguese  man  of  war. 
4.  Cirrigrada,  possessing  a  sort  of  cartilaginous  skeleton, 
and  furnished  with  appendages  called  cirri,  serving  as  oars 
and  for  prehension,  as  Porpita  and  Velella.  In  the  latter 
there  is  also  a  subcartilaginous  plate  rising  at  right  angles 
from  the  surface  supporting  a  delicate  membrane,  which 
acts  as  a  sail. 

This  classification  has  been  laid  aside  since  the  micro- 
scopic discovery  of  the  close  relationship  between  the 
Hydrozoa  and  the  Medusoid  Acalephs,  and  the  latter  are 
now  subdivided  into  the  "  naked-eyed  "  and  the  "  covered- 
eyed  "  Acalephs.  The  alternation  of  generations,  page 
126,  is  fully  illustrated  in  this  class.  The  embryo  emerges 
as  a  ciliated  gemmule,  resembling  one  of  the  Infusoria. 
One  end  contracts  and  attaches  itself  so  as  to  form  a  foot, 
while  the  other  enlarges  and  becomes  a  mouth,  from  which 
four  tubercles  sprout  and  become  tentacles.  Thus  a  Hy- 
dra-like polyp  is  formed,  which  acquires  additional  tenta- 
cles. From  such  a  polyp  many  colonies  may  rise  by  gem- 
mation or  budding,  but  after  a  time  the  polyp  becomes 
elongated,  and  constricted  below  the  mouth.  The  con- 
stricted part  gives  origin  to  other  tentacles,  while  similar 
constrictions  are  repeated  round  the  lower  parts  of  the 
body,  so  as  to  divide  it  into  a  series  of  saucer-like  disks, 
which  are  successively  detached  and  become  Medusae 
(Plate  XV,  Figs.  125,  126). 

VIII.  ECHINODERMS. — This  class  includes  the  star-fishes, 
the  sea-urchins  or  sea-eggs,  the  sea-slugs,  and  the  crinoids 
or  stone  lilies  of  former  ages.  If  we  imagine  a  polyp  with 


168  THE    MICROSCOPIST. 

a  long  stem  to  secrete  calcareous  matter,  not  merely  exter- 
nally, but  in  the  substance  of  its  body  and  tentacles,  such 
polyp  when  dried  would  present  some  such  appearance  as 
the  fossil  Encrinoid  Echinoderms  of  past  times.  The  im- 
agination of  such  a  polyp  without  a  stem,  and  having 
sucker-like  disks  on  its  arms,  will  give  us  the  picture  of 
a  star-fish  (Asterias).  Imagine  the  rays  diminished  and 
the  central  part  extended,  either  flat  or  globular,  and  we 
have  the  form  of  Echini  with  the  spines  removed.  The 
Holothurice  have  elongated  membranous  bodies,  with  im- 
bedded spiculae. 

The  structure  of  Echinoderms  is  quite  complex,  and 
belongs  to  comparative  anatomy  rather  than  microscopy, 
yet  some  directions  for  the  study  of  these  forms  is  essen- 
tial to  our  plan. 

Thin  sections  of  the  shells,  spines,  etc.,  may  be  made  by 
first  cutting  with  a  fine  saw,  and  rubbing  down  with  a 
flat  file.  They  should  be  smoothed  by  rubbing  on  a  hone 
with  water,  cemented  to  a  glass  slip  with  balsam,  and 
carefully  ground  down  to  the  required  thickness.  They 
may  be  mounted  in  fluid  balsam. 

Many  Echinoderms  have  a  sort  of  internal  skeleton 
formed  of  detached  plates  or  spiculse.  The  membranous 
integument  of  the  Holothuriae  have  imbedded  calcareous 
plates  with  a  reticulated  structure,  and  they  are  often 
furnished  with  appendages,  as  prickles,  spines,  hooks,  etc., 
which  form  beautiful  microscopic  objects. 

The  larva  of  an  Echinoderm  is  a  peculiar  zooid,  which 
develops  by  a  sort  of  internal  gemmation.  One  of  the 
most  remarkable  of  these  larvae  has  been  called  Bipin- 
naria. 

IX.  BRYOZOA  OR  POLYZOA. — Microscopic  research  has 
removed  this  class  from  the  polyps,  which  they  resemble, 
to  the  molluscan  sub-kingdom.  They  have  a  group  of 
ciliated  tentacles  round  the  mouth,  but  have  a  digestive 
system  far  more  complex  than  polyps.  They  form  delicate 


PLATE  XV. 


FIG.  125. 


Development  of  Medusa  buds  in  Syn- 
choryna  Sarsii. 

FIG  126. 


A,  Portion  of  Cellularia  cilia/a,  enlarged ;  B, 
one  of  the  "  bird's-head  "  of  Evgula  avicularia, 
more  highly  magnified,  and  seen  in  the  act  of 
grasping  another. 

FIG.  128. 


d  d 

Successive  stages  of  development  of  Medusa 
buds  from  Strobila  larva. 


Sertularia  cupresaina:—A,  natural  size: 
B,  portion  magnified. 


THE  MICROSCOPE  IN  ZOOLOGY.          169 

corals,  either  membranous  or  calcareous,  made  up  of  minute 
cabin-like  cells,  which  are  either  thin  crusts  on  sea-weeds, 
rocks,  etc.,  or  slender  moss-like  tufts,  or  groups  of  thin 
curving  plates,  or  net-like  fronds,  and  sometimes  thread- 
like lines  or  open  reticulations.  The  cells  of  a  group  have 
no  connection  with  a  common  tube,  as  the  Hydroids,  but 
the  alimentary  system  of  each  little  Bryozoon  is  indepen- 
dent. 

Many  of  the  Polyzoa  have  curious  appendages  to  their 
cells,  of  two  kinds ;  the  first  are  called  birds'-head  pro- 
cesses or  avicularia.  They  consist  of  a  body,  a  hinge  or 
lower  jaw-like  process,  and  a  stalk.  The  lower  portion  is 
moved  by  an  elevator  and  depressor  muscle,  and  during 
life  the  motion  is  constant.  The  second  kind,  or  vibracula, 
is  a  hollow  process  from  which  vibratile  filaments  project 
(Plate  XY,  Figs.  127,  128). 

X.  TUNICATA. — These  molluscs  are  so  named  from  the 
leathery  or  cartilaginous  tunic  which  envelops  them,  and 
which  often  contains  calcareous  spicula.  Like  the  Bryo- 
zoa  they  tend  to  produce  composite  structures  by  gemma- 
tion, but  they  have  no  ciliated  tentacles.  They  are  of 
most  interest  to  the  microscopist  from  the  peculiar  actions 
of  their  respiratory  and  circulatory  organs,  which  may  be 
seen  through  the  transparent  walls  of  small  specimens. 
The  branchial  or  respiratory  sac  has  a  beautiful  network 
of  bloodvessels,  and  is  studded  with  vibratile  cilia  for  dif- 
fusing water  over  the  membrane.  The  circulation  is  re- 
markable from  the  alternation  of  its  direction. 

The  smaller  Tunicata  are  usually  found  aggregate,  in- 
vesting rocks,  stones  and  shells,  or  sea-weeds ;  a  few  are 
free. 

Synopsis  of  the  Families. 

A.  Attached  ;  mantle  and  test  united  only  at  the  ori- 
fices. 

1.  Botryllidce. — Bodies  united  into  systems. 


170  THE    MICROSCOPIST. 

2.  Clavelinidce. — Bodies  distinct,  but  connected   by  a 
common  root  thread. 

3.  Ascidiadce. — Bodies  unconnected. 

B.  Free ;  mantle  and  test  united  throughout. 

4.  Pelonceadce. — Orifices  near  together. 

5.  Sal  pad  (B. — Orifices  at  opposite  ends. 

XI.  CONCHIFERA. — This  class  consists  of  bivalve  mol- 
luscs, and  is  chiefly  interesting  to  the  microscopist  from 
the  ciliary  motion  on  their  gills  and  the  structure  of  the 
shell. 

The  ciliary  motion  may  be  observed  in  the  oyster  or 
mussel,  by  detaching  a  small  piece  of  one  of  the  bands 
which  run  parallel  with  the  edge  of  the  open  shell,  placing 
it  on  a  glass  slide  in  a  drop  of  the  liquid  from  the  shell, 
separating  the  bars  with  needles,  and  covering  it  with 
thin  glass ;  or  the  fragment  may  be  placed  in  the  live  box 
and  submitted  to  pressure.  The  peculiar  movement  of 
each  cilium  requires  a  high  magnifying  power.  It  appears 
to  serve  the  double  purpose  of  aeration  of  the  blood  and 
the  production  of  a  current  for  the  supply  of  aliment. 

Dr.  Carpenter  has  shown  that  the  shells  of  molluscs 
possess  definite  structure.  In  the  Margaritaceaz  the  exter- 
nal layer  is  prismatic,  and  the  internal  nacreous.  The 
nacreous  or  iridescent  lustre  depends  on  a  series  of  grooved 
lines  produced  by  laminae  more  or  less  oblique  to  the  plane 
of  the  surface.  The  shells  of  Terebratidce  are  marked  by 
perforations,  which  pass  from  one  surface  to  another. 
The  rudimentary  shell  of  the  cuttle-fish  (of  the  class 
Cephalopoda],  or  "  cuttle-fish  bone,"  is  a  beautiful  object 
either  opaque  or  in  the  polariscope.  Sections  may  be 
made  in  various  directions  with  a  sharp  knife,  and 
mounted  as  opaque  objects  or  in  balsam. 

XII.  GASTEROPODA. — These  molluscs  are  either  naked, 
as  the  slug,  or  have  univalve  shells,  as  the  snail,  the  lim- 
pet, or  the  whelk.     As  in  the  other  classes  referred  to, 
the  details  of  anatomical  structure  are  full  of  interest ; 


PLATE  XVI. 


FIG.  130. 


FIG.  129. 


A,  female  of  Cyclops  quadricornis ; — a,  body ;  6,  tail ; 
c,  antenna  ;'d,  antennule;  e,  feet;  /,  plumose  setae  of 
tail ;— B,  tail,  with  external  egg-sacs  ;  c,  D,  E,  F,  G, 
successive  stages  of  development  of  young. 


FIG.  131. 


Metamorphosis  of  Carcinus  mcenas: — A,  first  stage  ;  B,  second  stage ;  c,  third  stage, 
in  which  it  begins  to  assume  the  adult  form ;  D,  perfect  form. 


THE  MICROSCOPE  IN  ZOOLOGY.          171 

but  to  the  microscopist  the  palate,  or  tongue  as  it  is  called 
— a  tube  which  passes  beneath  the  mouth,  opening  ob- 
liquely in  front,  and  which  is  covered  with  transverse 
rows  of  minute  teeth  set  upon  plates — presents  characters 
of  great  value  in  classification.  These  palates  require 
careful  dissection,  and  when  mounted  in  balsam  become 
beautiful  polariscope  objects  (Plate  XVI,  Fig.  129). 

XIII.  CEPHALOPODA. — The  crystalline  lens  in  the  eye  of 
the  cuttle-fish  is  said  to  be  of  the  same  form  as  the  well- 
known  "  Coddington  lens."     The  skin  of  this  class  con- 
tains a  curious  provision  for  changing  its  hue,  consisting 
of  large  pigment-cells  containing  coloring  matter  of  vari- 
ous tints. 

The  suckers,  or  prehensile  disks,  on  the  arms  of  cephal- 
opods  often  make  interesting  opaque  objects  when  dried. 

XIV.  ENTOZOA. — These  are  parasitic  animals  belonging 
to  the  class  of  worms.     They  are  characterized  by  the 
absence  or  low  development  of  the  nutritive  system,  and 
the  extraordinary  development  of  their  reproductive  or- 
gans.    Thus  the  Tvenia  or  tapeworm  has  neither  mouth 
nor  stomach,  the  so-called  "  head  "  being  merely  an  organ 
for  attachment,  while  each  segment  of  the  "  body  "  con- 
tains repetitions  of  a  complex  generative  apparatus. 

Among  the  Kematoid  or  round  worms,  the  Anguilhdaz, 
or  little  eel-like  worms,  found  in  sour  paste,  vinegar,  etc., 
as  well  as  the  Trichina  spir.alis,  inhabiting  the  voluntary 
muscles,  are  generally  classified. 

ORDER  I.  STERELMINTHA. — Alimentary  canal  absent  or 
indistinct. 

FAMILY  1.  Cestoidea. — Tapeworms;  body  strap-shaped, 
divided  into  transverse  joints ;  alimentary  canal  indistinct. 
The  cystic  Entozoa  (Echinococcus,  etc.)  are  nurse  or  larval 
forms  of  Cestoidea. 

FAMILY  2.  Trematoda. — Body  mostly  flattened ;  alimen- 
tary canal  distinct ;  branched. 


172  THE    MICROSCOPIST. 

FAMILY  3.  Acanthocephala. — Body  flattened,  transversely 
wrinkled  ;  sexual  organs  in  separate  individuals. 

FAMILY  4.  Gordiawa  (Hairworms). — Body  filamentous, 
cylindrical ;  alimentary  canal  present ;  sexes  distinct. 

FAMILY  5.  Protozoidea  or  G-regarinida. — Probably  larval 
forms. 

ORDER  II.  CJELELMINTHA. — Alimentary  canal  distinct. 

FAMILY  1.  Nematoidea  (Roundworms). — Body  cylindri- 
cal, hollow ;  sexes  separate. 

The  Enoplidce,  tribe  is  distinguished  by  an  armature  of 
hooks  or  styles  round  the  mouth.  Most  of  them  are 
microscopic. 

XY.  ANNUL  AT  A  (Red-blooded  Worms). — Some  of  these, 
as  the  Serpula,  etc.,  are  inclosed  in  tubes  formed  of  a  shelly 
secretion,  or  built  up  of  grains  of  sand,  etc.,  agglutinated 
together.  Many  have  special  respiratory  appendages  to 
their  heads,  in  which  the  microscope  will  exhibit  the  cir- 
culation. The  worms  of  the  Nais  tribe,  also,  are  so  trans- 
parent as  to  be  peculiarly  fitted  for  microscopic  study  of 
structure.  The  dental  apparatus  of  the  leech  consists  of 
a  triangular  aperture  in  a  sucking  disk,  furnished  with 
three  semicircular  horny  plates,  each  bordered  with  a  row 
of  eighty  to  ninety  teeth,  which  act  like  a  saw. 

ORDER  1.  TURBELLARIA. — Body  bilateral,  soft,  covered 
with  vibratile  cilia,  not  segmented ;  eyes  distinct ;  sexless 
or  hermaphrodite. 

ORDER  2.  SUCTORIA  (Apoda). — Body  elongate,  ringed, 
without  bristles  or  foot-like  tubercles ;  locomotion  by 
sucking-disks  ;  no  external  branchiae. 

ORDER  3.  SETIGRADA  (Choetopoda). — Body  ringed,  elon- 
gate, with  feet  or  setigerous  rudiments  of  them  ;  external 
branchiae  usually  present. 

XYI.  CRUSTACEA. — In  the  family  of  Isopoda  the  micros- 
copist  will  find  the  Ascellus  vulgaris,  or  water  wood-louse, 
of  great  interest,  as  readily  exhibiting  the  dorsal  vessel 
and  circulating  fluids. 


THE  MICROSCOPE  IN  ZOOLOGY.          173 

The  family  of  Entomostraca  contains  a  number  of  gen- 
era, nearly  all  of  which  are  but  just  visible  to  the  naked 
eye.  They  are  distinguished  by  the  inclosure  of  the  body 
in  a  horny  or  shelly  case,  often  resembling  a  bivalve  shell, 
though  sometimes  of  a  single  piece.  The  tribe  of  Lophy- 
ropoda  (bristly -footed),  or  "  water-fleas,"  is  divided  into 
two  orders,  the  first  of  which,  Ostracoda,  is  characterized 
by  a  bivalve  shell,  a  small  number  of  legs,  and  the  absence 
of  an  external  ovary.  A  familiar  member  of  this  order, 
the  little  Cypris,ia  common  in  pools  and  streams,  and  may 
be  recognized  by  its  two  pairs  of  antennae,  the  first  of 
which  is  jointed  and  tufted,  while  the  second  is  directed 
downwards  like  legs.  It  has  two  pairs  of  legs,  the  poste- 
rior of  which  do  not  appear  outside  the  shell. 

The  order  Copepoda  has  a  jointed  shell,  like  a  buckler, 
almost  inclosing  the  head  and  thorax.  To  this  belongs 
the  genus  Cyclops  (named  from  its  single  eye),  the  female 
of  which  carries  on  either  side  of  the  abdomen  an  egg 
capsule,  or  external  ovarium,  in  which  the  ova  undergo 
their  earlier  stages  of  development  (Plate  XYI,  Fig.  130). 

The  Daphnia  pulex,  or  arborescent  water-flea,  belongs  to 
the  order  Cladocera  and  tribe  Branchiopoda.  The  other 
order  of  this  tribe,  the  Phyllopoda,  has  the  body  divided 
into  segments,  furnished  with  leaf-like  members  or  "  fin 
feet." 

When  first  hatched,  the  larval  Entomostraca  differ 
greatly  from  the  adult.  The  larval  forms  of  higher 
Crustacea  resemble  adult  Entomostraca. 

The  suctorial  Crustacea,  order  Siphonostoma,  are  gener- 
ally parasitic,  mostly  affixed  to  the  gills  of  fishes  by  means 
of  hooks,  arms,  or  suckers,  arising  from  or  consisting  of 
modified  foot-jaws.  The  transformations  in  this  order,  as 
in  the  Lerncea,  seem  to  be  a  process  of  degradation.  The 
young  comes  from  the  egg  as  active  as  the  young  of 
Cyclops,  which  they  resemble,  and  pass  through  a  series 
of  metamorphoses  in  which  they  cast  off  their  locomotive 


174  THE    MICROSCOPIST. 

members  and  their  eyes.     The  males  and  females  do  not 
resemble  each  other. 

The  order  Cirrhipeda  consists  of  the  barnacles  and  their 
allies.  In  their  early  state  they  resemble  the  Entomos- 
traca,  are  unattached,  and  have  eyes.  After  a  series  of 
metamorphoses  they  become  covered  with  a  bivalve  shell, 
which  is  thrown  off;  the  animal  then  attaches  itself  by 
its  head,  which  in  the  barnacle  becomes  an  elongated 
pedicle,  and  in  Balanus  expands  into  a  disk.  The  first 
thoracic  segment  produces  the  "multivalve"  shell,  while 
the  other  segments  evolve  the  six  pairs  of  cirrhi,  which 
are  slender,  tendril-like  appendages,  fringed  with  ciliated 
filaments. 

In  the  order  Amphipoda,  the  Gammarus  pulex,  or  fresh- 
water shrimp,  and  the  Talitrus  saltator,  or  sandhopper, 
may  be  interesting  to  the  microscopist. 

The  order  Decapoda,  to  which  belong  the  crab,  lobster, 
shrimp,  etc.,  is  of  interest,  from  the  structure  of  the  shell 
and  the  phenomena  of  metamorphosis.  The  shell  usually 
consists  of  a  horny  structureless  layer  exteriorly,  an  areo- 
lated  stratum,  and  a  laminated  tubular  substance.  The 
difference  between  the  adult  and  larval  forms  in  this  order 
is  so  great  that  the  young  crab  was  formerly  considered 
a  distinct  germs,  Zoea  (Plate  XVI,  Fig.  131). 

For  the  preservation  of  specimens  of  Crustacea,  Dr. 
Carpenter  recommends  glycerin  jelly  as  the  best  medium. 

XVII.  INSECTS. — Many  insects  may  be  mounted  dry, 
as  opaque  objects.  They  may  be  arranged  in  position  by 
the  use  of  hot  water  or  steam.  Those  which  are  trans- 
parent enough  may  be  mounted  in  balsam,  and  very  deli- 
cate ones  in  fluid.  To  display  the  external  chitinous  cov- 
ering of  an  entire  insect,  it  may  be  soaked  in  strong  liquor 
potassee,  and  the  internal  parts  squeezed  out  in  a  saucer 
of  water  by  gently  rolling  over  it  a  camel's-hair  brush. 
It  may  be  put  on  a  slide,  and  the  cover  fastened  by  tying 
with  a  thread.  It  should  then  be  soaked  in  turpentine 


THE  MICROSCOPE  IN  ZOOLOGY.         175 

until  quite  transparent,  when  it  may  be  removed,  the  tur- 
pentine partially  drained  off,  and  a  solution  of  balsam  in 
chloroform  allowed  to  insinuate  itself  by  capillary  attrac- 
tion. Gentle  heat  from  a  spirit-lamp  will  be  useful  at  this 
stage  of  the  mounting. 

Small  insects  hardly  need  soaking  in  caustic  potash,  as 
turpentine  or  oil  of  cloves  will  render  them  after  awhile 
quite  transparent,  and  their  internal  organs  are  beautifully 
seen  in  the  binocular  microscope.  Thin  sections  of  insects 
are  instructive,  and  may  be  made  with  a  section-cutter  by 
first  saturating  the  body  with  thick  gum  mucilage,  and 
then  incasing  in  melted  paraffin. 

Many  insects  and  insect  preparations  are  well  preserved 
in  glycerin. 

The  eggs  of  insects  are  often  interesting  objects,  and 
should  be  mounted  in  fluid. 

Wing  cases  of  beetles  are  often  very  brilliant  opaque 
objects.  Some  are  covered  with  iridescent  scales,  and 
others  have  branching  hairs.  Many  are  improved  by 
balsam,  and  this  may  be  determined  by  touching  with 
turpentine  before  mounting. 

Scales  of  Lepidoptefa,  etc.,  may  be  exhibited  in  their 
natural  arrangement  by  mounting  a  small  piece  of  wing 
dry.  If  desired  as  test  objects,  a  slide  or  thin  cover,  after 
having  been  breathed  on,  may  be  slightly  pressed  on  the 
wing  or  body  of  the  insect.  The  scales  are  really  flattened 
cells,  analogous  to  the  epidermic  cells  of  higher  animals. 
Some  have  their  walls  strengthened  by  longitudinal  ribs, 
while  others,  as  the  Podurce,  show  a  beaded  appearance 
under  high  powers  from  corrugation.  Dr.  Carpenter  be- 
lieves the  exclamation  marks  in  the  scales  of  the  latter  to 
be  the  most  valuable  test  of  the  excellence  of  an  objective. 

Hairs  of  insects  are  often  branched  or  tufted.  The  hair 
of  the  bee  .shows  prismatic  colors  if  the  chromatic  aberra- 
tion of  the  object-glass  is  not  exactly  neutralized. 

Antennae  vary  greatly  in  form,  and  are  often  useful  in 


176  THE    MICROSCOPIST. 

classification  (Plate  XVII,  Fig.  132).  Thus  in  the  Cole- 
optera  we  have  the  Serricornes^  or  serrated  antennae;  the 
Clavicornes,  or  clubbed  ;  the  Palpicornes,  with  antennae  no 
larger  than  palpi ;  the  Lamellicornes,  with  leaf-like  appen- 
dages to  the  antennae ;  and  the  Longicornes,  with  antennae 
as  long  or  longer  than  the  body.  Xerve-fibres,  ending  in 
minute  cavities  in  the  antennae,  have  been  traced,  which 
are  supposed  to  be  organs  of  hearing.  The  antennae  should 
be  bleached  to  exhibit  them.  The  bleaching  process  is 
also  useful  for  other  parts  of  insects.  The  bleaching  fluid 
consists  of  a  drachm  of  chlorate  of  potass  in  about  two 
drachms  of  water,  to  which  is  added  about  a  drachm  of 
hydrochloric  acid. 

Compound  eyes  of  insects  are  always  interesting.  They 
are  quite  conspicuous,  and  often  contain  thousands  of 
facets,  or  minute  eyes,  called  ocelli  (Plate  XVII,  A  B,  Fig. 
133).  Besides  these,  insects  possess  rudimentary  single 
eyes,  like  those  of  the  Arachnidce.  These  are  at  the  top 
of  the  head,  and  are  termed  stemmata  (Plate  XVII,  a, 
Fig.  133).  To  display  the  "  corneules,"  or  exterior  layer 
of  the  compound  eye,  the  pigment  must  be  carefully 
brushed  away  after  maceration.  A  number  of  notches 
may  then  be  made  around  the  edge,  the  membrane  flat- 
tened on  a  slide,  and  mounted  in  balsam.  Vertical  sec- 
tions may  be  made  while  fresh,  so  as  to  trace  the  relations 
of  the  optic  nerve,  etc.  The  dissecting  microscope  and 
needles  will  be  found  useful  (Plate  XVII,  Fig.  132). 

Mouths  of  insects  present  great  varieties.  In  the  beetles 
the  mouth  consists  of  a  pair  of  mandibles,  opening  later- 
ally ;  a  second  pair,  called  maxillae ;  a  labrum  or  upper 
lip ;  an  under  lip  or  labium  ;  one  or  two  pairs  of  jointed 
appendages  to  the  maxillae,  termed  maxillary  palpi ;  and 
a  pair  of  labial  palpi.  The  labium  is  often  composed  of 
distinct  parts,  the  first  of  which  is  called  the  mentum  or 
chin,  and  the  anterior  part  the  ligula  or  tongue.  This 
latter  part  is  greatly  developed  in  the  fly,  and  presents 


Fio.  132. 


Tongue  of  common  Fly. 


Foot  of  Fly. 


FIG.  136. 


Tracheal  system  of  Nepa  (Water-scorpion). 


THE  MICROSCOPE  IN  ZOOLOGY.          177 

a  curious  modification  of  tracheal  structure,  which  is 
thought  to  serve  the  function  of  suction  (Plate  XVII, 
Fig.  134).  The  tongue  of  the  bee  is  also  an  interesting 
object.  In  the  Diptera  the  labrum,  maxillae,  mandibles, 
etc.,  are  converted  into  delicate  lancets,  termed  setae,  and 
are  used  to  puncture  the  epidermis  of  animals  or  plants, 
from  which  the  juices  may  be  drawn  by  the  proboscis. 
In  the  Lepidoptera  the  labrum  and  mandibles  are  reduced 
to  minute  plates,  while  the  maxillae  are  greatly  elongated, 
and  are  united  to  form  the  haustellum,  or  true  proboscis, 
which  contains  a  tube  for  suction. 

Feet. — These  organs  vary  with  the  habits  of  life  in  dif- 
ferent species.  The  limb  consists  of  five  divisions :  the 
coxa  or  hip,  the  trochanter,  the  femur  or  thigh,  the  tibia 
or  shank,  and  the  tarsus  or  foot.  This  last  has  usually 
five  joints,  but  sometimes  less.  The  Coleoptera  are  subdi- 
vided into  groups,  according  as  the  tarsus  consists  of  five, 
four,  or  three  segments.  The  last  joint  is  furnished  with 
hooks  or  claws,  and  in  the  fly,  etc.,  the  foot  is  also 
furnished  with  membranous  expansions,  called  pulvilli. 
These  latter  have  numerous  hairs,  each  of  which  has  a 
minute  disk  at  its  extremity.  By  these,  probably  by  the 
secretion  of  a  viscid  material,  the  insect  is  enabled  to 
walk  on  glass,  etc.,  in  opposition  to  gravity  (Plate  XVII, 
Fig.  135).  In  the  Dytiscus,  the  inner  side  of  the  leg  is 
furnished  with  disks  or  suckers  of  considerable  size. 
They  may  be  mounted  as  opaque  objects.  Stings  and 
Ovipositors  also  present  a  great  variety  of  structure,  and 
may  be  best  mounted  in  balsam. 

The  alimentary  canal  in  insects  presents  many  diversi- 
ties. As  in  higher  animals,  it  is  shorter  in  flesh-eaters 
than  in  feeders  on  vegetables.  It  consists  of:  1.  The 
oesophagus,  which  is  sometimes  dilated  to  form  a  crop. 

2.  The  muscular  stomach,  or  gizzard,  whose  lining  mem- 
brane is  covered  with  plates,  or  teeth,  for  trituration. 

3.  A  cylindrical  true  stomach,  in  which  digestion  takes 

12 


178  THE    MICROSCOPIST. 

place.  4.  The  small  intestine,  terminating  in  5,  the  large 
intestine  or  colon.  The  colon  of  most  insects  in  the 
imago  or  perfect  state,  never  in  larvae  or  pupae,  contains 
from  four  to  six  organs  of  doubtful  nature  arranged  in 
pairs.  They  are  transparent,  round,  or  oval  tubercles 
projecting  inside  the  colon,  traversed  by  tufts  of  tracheae, 
and  sometimes  with  a  horny  ring  at  the  base. 

The  salivary  glands  are  sacs  or  tubes  of  variable  form 
and  length,  terminating  near  the  mouth.  A  distinct  liver 
is  absent,  its  function  being  performed  by  glandular  cells 
in  the  walls  of  the  stomach.  Many  insects,  however, 
have  caecal  appendages  to  the  stomach  which  secrete  bile. 
Some  have  tubular  caeca  appended  to  the  small  intestine, 
probably  representing  a  pancreas.  In  the  interspaces  of 
the  various  abdominal  organs,  is  found  a  curious  organ 
called  the  fatty  body,  which  attains  its  development  at 
the  close  of  the  larval  period,  and  appears  to  form  a  res- 
ervoir of  nourishment  for  the  pupa.  It  consists  of  fat- 
cells  imbedded  in  a  reticular  tissue,  and  is  traversed  by 
slender  tracheae. 

The  Malpighian  vessels  are  slender,  mostly  tubular 
glands,  caecal  or  uniting  with  each  other,  which  open  into 
the  pyloric  end  of  the  stomach,  and  as  uric  acid  has  been 
found  in  them,  are  thought  to  serve  the  functions  of  a 
kidney.  Some  consider  the  renal  organ  to  be  represented 
by  certain  long  vessels  convoluted  on  the  colon,  and  open- 
ing near  the  anus. 

Other  glandular  organs  occur  in  insects,  as  cysts  in  the 
integument,  called  glandulae  odoriferae ;  poison  glands, 
attached  to  the  sting  in  many  females;  and  silk-secreting 
glands,  coiled  in  the  sides  of  the  body  and  opening  out- 
side the  mouth. 

The  heart  is  a  long  contractile  vessel  situated  in  the 
back.  It  is  constricted  at  intervals.  The  posterior  part 
acts  as  a  heart,  and  the  anterior  represents  an  aorta,  and 
conveys  blood  to  the  body.  From  the  anterior  end  the 


THE  MICROSCOPE  IN  ZOOLOGY.          179 

olood  passes  in  currents  in  all  directions,  without  vascular 
walls,  running  into  the  antennae,  wings,  extremities,  etc., 
and  returning  as  a  venous  current,  forming  two  lateral 
currents  towards  the  end  of  the  ahdomen,  it  is  brought 
by  the  diastole  of  the  heart  through  lateral  fissures  ex- 
isting in  it. 

The  respiration  is  effected  by  means  of  tracheae,  two 
or  more  large  vessels  running  longitudinally,  giving  off 
branches  in  all  directions,  and  opening  to  the  air  by  short 
tubes,  connected  at  the  sides  of  the  body  with  orifices 
called  spiracles.  Aquatic  larvae  often  have  branchiae  in 
the  form  of  plates,  leaves,  or  hairs,  through  which  the 
tracheae  ramify  (Plate  XVII,  Fig.  136). 

The  nervous  system  consists  of  a  series  of  ganglia  ar- 
ranged in  pairs,  one  for  each  segment  of  the  body.  They 
are  situated  between  the  alimentary  canal  and  the  under 
surface  of  the  body,  and  are  usually  connected  by  longi- 
tudinal nervous  cords.  From  the  ganglia  nerves  are  dis- 
tributed to  all  parts. 

The  muscular  system  of  insects  is  quite  extensive.  Ly- 
onet  dissected  and  described  more  than  four  thousand  in 
the  caterpillar  of  the  goat-moth  (Cossus  ligniperda). 

XVIII.  ARACHNID  A. — This  class  of  animals  includes 
mites,  ticks,  spiders,  and  scorpions.  They  are  destitute 
of  antennae ;  the  head  and  thorax  are  united ;  they  have 
simple  eyes  (ocelli),  and  eight  jointed  legs. 

The  cheese-mite,  the  u  ticks,"  the  itch-insect  (Sarcoptes 
scabies),  and  the  Demodex  folliculorum,  which  is  parasitic 
in  the  sebaceous  follicles  of  the  skin  of  the  face,  are  com- 
mon examples  of  Acari.  They  are  best  mounted  in  fluid. 

The  respiratory  apparatus  in  spiders  differs  from  that 
of  insects,  the  spiracles  opening  into  respiratory  sacs,  which 
contain  leaf-like  folds  for  aeration  of  blood.  The  spinning 
apparatus  is  also  interesting. 

The  minute  anatomy  of  vertebrated  animals  affords  the 


180  THE    MICROSCOPIST. 

microscopist  numerous  specimens,  but  the  details  will  be 
best  understood  from  the  following  chapter. 

As  the  classification  of  the  Invertebrata  is  subject  to 
great  variation,  the  following  table,  after  Nicholson,  is 
added  for  the  sake  of  comparison  : 

INYERTEBRATE  ANIMALS. 

SUB-KINGDOM   I. — PROTOZOA. 

CLASS  I.  GREGARINID^;, — Parasitic  Protozoa,  destitute 
of  a  mouth,  and  destitute  of  pseudopodia.  Ex.,  Gregarina. 

CLASS  II.  RHIZOPODA. — Simple  or  compound  ;  destitute 
of  a  mouth ;  capable  of  putting  forth  pseudopodia. 

CLASS  III.  INFUSORIA. — Generally  with  a  mouth ;  no 
pseudopodia;  with  vibratile  cilia  or  contractile  filaments. 

SUB-KINGDOM  II. — CCELENTERATA. 

CLASS  I.  HYDROZOA. — Walls  of  the  digestive  sac  not 
separated  from  those  of  the  body  cavity  ;  reproductive 
organs  external. 

Sub-class  1.  Hydroida. — Ex.,  Hydra.  Tubularia  (pipe- 
coralline).  Sertularia  (sea-fir). 

Sub-class  2.  Siphonophora. — Ex.,  Diphyes.  Physalia 
(Portuguese  man-of-war). 

Sub-class  3.  Discopkora. — Ex.,  !N"aked-eyed  Medusae,  or 
Jelly-fish. 

Sub-class  4.  Lucernarida. — Ex.,  Sea-nettles,  or  "  Hidden- 
eyed  "  Medusae. 

CLASS  II.  ACTINOZOA. — Digestive  sac  distinct  from  the 
general  cavity,  but  opening  into  it ;  reproductive  organs 
internal. 

Order  1.  Zoantharid. — Ex.,  Sea-Anemones  (Actinia). 
Reef-building  corals. 

Order  2.  Alcyonaria. — Ex.,  Sea-pen.     Red  coral. 

Order  3.  Ctenophora. — Ex.,  Cestum  (Yenus's  girdle). 


THE    MICROSCOPE    IN    ZOOLOGY.  181 

SUB-KINGDOM  III. — ANNULOIDA. 

CLASS  I.  ECHINODERM  AT  A.— Integument  calcareous  or 
leathery ;  adult  radiate. 

Order  1.  Crinoidea. — Ex.,  Comatula. 

Order  2.  Blastoidea.— (Extinct.) 

Order  3.   Cystoidea. — (Extinct.) 

Order  4.   Ophiuroidea. — Ex.,  Brittle-star. 

Order  5.  Aster  oidea.—  Ex.,  Star-fish. 

Order  6.  Echinoidea. — Ex.,  Sea-urchins. 

Order  7.  Holothur  oidea. — Ex.,  Sea-cucumbers. 

CLASS  II.  SCOLECIDA. — Soft-bodied,  cylindrical,  or  flat ; 
nervous  system  not  radiate  ;  of  one  or  two  ganglia. 

Order  1.   Tceniada. — Ex.,  Tapeworms. 

Order  2.   Trem,atoda.—Y.x.,  Flukes. 

Order  3.   Tarbellaria — Ex.,  Planarians. 

Order  4.  Acanthocephala. — Ex.,  Echinorynchus. 

Order  5.  Gordiacea. — Ex.,  Hairworms. 

Order  6.  Nematoda. — Ex.,  Round  worms. 

Order  7.  Rotifera. — Ex.,  Wheel  animalcules. 

SUB-KINGDOM   IV. — ANNULOSA. 

DIVISION  A.  ANARTHROPODA. — Locomotive  appendages 
not  distinctly  jointed  or  articulated  to  the  body. 

CLASS  I.  GEPHYREA. — Ex.,  Spoon-worms. 

CLASS  II.  ANNELIDA.  —  Ex.,  Leeches  (Hirundinidse). 
Earth-worms  (Oligochseta).  Tube-worms  (Tubicola). 
Sand-worms  and  Sea-worms  (Errantia). 

CLASS  III.  CH^TOGNATHA. — Ex.,  Sagitta. 

DIVISION  B.  ARTHROPODA.  —  Locomotive  appendages 
jointed  to  the  body. 

CLASS  I.  CRUSTACEA. — Ex.,  Decapoda.  Isopoda.  Xi- 
phosura.  Cirripedia. 

CLASS  II.  ARACHNIDA. — Ex.,  Podosomata  (sea-spiders). 
Acarina  (mites).  Pedipalpi  (scorpions).  Araneida  (spi- 
ders). 


182  THE    MICROSCOPIST. 

CLASS  III.  MYRIAPODA. — Ex.,  Centipedes. 

CLASS  IV.  INSECTA.—  Ex.,  Anoplura  (lice).  Mallophaga 
(bird  lice).  Thysanura  (spring-tails).  Hemiptera.  Or- 
thoptera.  Neuroptera.  Diptera.  Lepidoptera.  Hyme- 
noptera.  Coleoptera. 

SUB-KINGDOM   V. — MOLLUSCA. 

DIVISION  A.  MOLLUSCOIDA. — A  single  ganglion,  or  pair 
of  ganglia ;  heart  imperfect,  or  none. 

CLASS  I.  POLYZOA. — Ex.,  Sea-mats  (Flustra). 

CLASS  II.  TUNIC  AT  A. — Ex.,  Ascidia  (Sea-squirts). 

CLASS  III.  BRACHIOPODA. — Ex.,  Terebratula. 

DIVISION  B.  MOLLUSCA  PROPER. — Three  pairs  of  gan- 
glia ;  heart  of  at  least  two  chambers. 

CLASS  I.  LAMELLIBRANCHIATA. — Ex.,  Oyster.     Mussel. 

CLASS  II.  GASTEROPODA.  —  Ex.,  Buccinium.  Helix. 
Doris. 

CLASS  III.  PTEROPODA. — Ex.,  Cleodora. 

CLASS  IY.  CEPHALOPODA. 

Order  1.  Dibranchiata. — Ex.,  Poulp.     Paper  Nautilus. 

Order  2.   Tetrabranchiata. — Ex.,  Pearly  Nautilus. 


CHAPTER  XII. 

THE   MICROSCOPE   IN   ANIMAL    HISTOLOGY. 

IN  Chapter  IX  we  described  the  elementary  living 
substance,  or  bioplasm,  from  which  all  organized  struc- 
tures proceed,  with  an  outline  of  its  morphology,  chemis- 
try, and  physiology.  In  Chapter  X  we  treated  of  Vege- 
table Histology,  or  the  elementary  tissues  and  organs 
which  pertain  to  vegetable  life.  We  now  consider  the 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          183 

structure  of  formed  material  in  animals,  with  special 
reference  to  the  minute  anatomy  of  the  human  body. 
Following  the  generalization  of  Dr.  Beale,  page  118,  we 
may  classify  histological  structures  as  follows  : 

A.  INORGANIC  AND  ORGANIC  ELEMENTS  OR  PABULUM. 

Resulting  in 

B.  BIOPLASM  ;  or,  O.  II.  C.  and  K,  with   other  chemical 

elements,  plus,  The  cause  of  life. 
From  this  results : 

C.  FORMED  MATERIAL,  consisting  of, 

I.  CHEMICAL  PRODUCTS  ;  Organic  Compounds,  etc. 

II.  MORPHOLOGICAL  PRODUCTS.   1.  Granules;  2.  Globules; 

3.  Fibres ;  4.  Membrane. 
Forming  Tissues.     1.  Simple  ;  2.  Compound. 
Arranged  in  Organs.     1.  Vegetative  ;  2.  Animal. 

I.  THE  CHEMICAL  PRODUCTS  of  Bioplasm  are  very  nu- 
merous, and  belong  to  the  science  of  Histo-Chemistry. 
Our  plan  allows  us  to  do  little  more  than  to  enumerate 
the  principal  groups.  It  has  already  been  stated  that  the 
true  chemical  structure  of  bioplasm,  or  living  sarcode, 
(protoplasm  in  a  living  state)  is  unknown,  since  it  is  only 
possible  to  analyze  the  dead  cell  substance.  Of  the  rela- 
tion of  the  oxygen,  hydrogen,  carbon,  and  nitrogen,  etc., 
which  constitute  its  "physical  basis,"  we  can  only  specu- 
late, or  imagine.  See  Chemistry  of  Cells  and  their  Products, 
page  122. 

The  chemical  transformations  of  cell-substance  into 
"  formed  material  "  consist  chiefly,  with  water  and  min- 
eral matter,  of  certain  groups  of  organic  principles,  some- 
times called  albuminous  or  "protein"  substances,  and 
their  nearer  derivatives,  as  glutin-yielding  and  elastic 
matter,  with  fat  and  pigments.  These  materials  are  sub- 
ject to  constant  secondary  changes  or  transformations, 


184  THE    MICROSCOPIST. 

since  they  are  not  laid  down  in  the  living  body  once  for 
all.  They  are  also  subject  to  constant  decay,  or  ultimate 
decomposition.  Histo-Chemistry  must,  therefore,  be  always 
a  difficult  study,  since  we  can  rarely  isolate  the  tissues  for 
examination,  nor  always  tell  when  a  substance  is  super- 
fluous aliment,  formative  or  retrogressive  material.  From 
a  limited  number  of  formative  or  histogenic  materials,  we 
have  a  host  of  changed  or  decomposition  products. 

Frey's  Histology  and  Histo-Chemistry,  Strieker's  Hand- 
book of  Histology,  and  Beale's  Bioplasm,  are  among  the 
most  useful  books  to  the  student  in  this  department. 

Frey  subdivides  the  groups  of  organic  principles  as  fol- 
lows : 

I.  Albuminous  or  Protein  Compounds. — Albumen.     Fi- 
brin.   Myosin.    Casein.    Globulin.    Peptones.    Ferments  ? 

II.  Hwmoglobulin. 

III.  Formative  (Histogenic}  Derivatives  from  Albuminous 
Substances. — Keratin.     Mucin.     Colloid.     Glutin-yielding 
substances.    Collagin  and  Glutin.    Chondrigen  and  Chon- 
drin.     Elastin. 

IV.  Fatty  Acids  and    Fats. — Glycerin.     Formic   acid. 
Acetic  acid.    Butyric  acid.    Capronic  acid.    Palmitic  acid. 
Stearic  acid.     Oleic  acid.     Cerebrin.     Cholesterin. 

V.  Carbohydrates. — The  Grape-sugar  group,  Cane-sugar 
group,    and    Cellulose    group;    or    Glycogen.     Dextrin. 
Grape-sugar.     Muscle-sugar.     Sugar  of  milk. 

VI.  Non-Nitrogenous  Acids. — Lactic.    Oxalic.    Succinic. 
Carbolic.     Taurylic. 

VII.  Nitrogenous    Acids. — Inosinic.     Uric.     Hippuric. 
Glycocholic.     Taurocholic. 

VIII.  Amides,  Amido  Acids,  and  Organic  Bases. — Urea. 
Guanin.     Xanthin.     Allantoin.     Kreatin.     Leucin.     Ty- 
rosin.     Glycin.     Cholin  (Neurin).     Taurin.     Cystin. 

IX.  Animal    Coloring    Matters. — Hrematin.     tLemin. 
ILiematoidin.     Urohsematin.    Melalin.    Biliary  pigments. 

X.  Cyanogen  Compounds. — Sulpho-cyanogen. 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          185 

XL  Mineral  Constituents. — Oxygen,  Nitrogen,  Carbonic 
acid.  Water.  Hydrochloric  acid.  Silicic  acid.  Calcium 
compounds  (Phosphate,  Carbonate,  Chloride,  and  Fluor- 
ide). Magnesium  compounds  (Phosphate.  Carbonate. 
Chloride).  Sodium  compounds  (Chloride.  Carbonate. 
Phosphate.  Sulphate).  Potassium  compounds  (Chloride. 
Carbonate.  Phosphate.  Sulphate).  Salts  of  Ammonium 
(Chloride.  Carbonate).  Iron  and  its  Salts  (Protochloride. 
Phospbate).  Manganese.  Copper. 

The  subject  of  Histology  relates  properly  to  cell-struc- 
ture (already  described,  Chapter  IX),  and  its  morpho- 
logical products,  yet  its  close  connection  with  Histo-chem- 
istry  renders  the  foregoing  list  of  substances  valuable  to 
the  stu dent- 
il. HISTOLOGICAL  STRUCTURE  is  due  to  the  formative 
power  of  bioplasm,  or  living  cell-substance,  and  is  not  mere 
selection  and  separation  from  pabulum,  or  aliment,  since 
from  the  same  pabulum,  and,  so  far  as  we  can  see,  under 
the  same  circumstances,  result  tissues  having  different 
physical  and  chemical  properties. 

In  our  classification  we  have  arranged  the  microscopic, 
or  histological,  elements  of  the  tissues  as  Granules,  Glob- 
ules, Fibre,  and  Membrane. 

Granules  are  minute  particles  of  formed  material. 

Globules  are  small,  homogeneous,  round,  or  oval  bodies. 
If  composed  of  albuminous  matter  they  are  rendered  trans- 
parent by  acetic  acid,  and  are  dissolved  by  potash  and 
soda.  If  consisting  of  fat  they  are  soluble  in  ether  and 
unaltered  by  acetic  acid.  If  they  are  earthy  matters  they 
are  dissolved  by  acids  and  unchanged  by  alkalies. 

Fibres  appear  as  fine  lines,  cylindrical  threads,  or  flat- 
tened bands,  parallel,  or  at  various  angles. 

Membrane  is  an  expansion  of  material.  It  may  be  trans- 
parent and  homogeneous,  and  may  be  recognized  by  plaits 
or  folds,  which  sometimes  simulate  fibres,  or  it  may  be 
granular,  or  bear  earthy  particles. 


186  THE    MICROSCOPIST. 

From  these  elements  result  the  simple  and  compound 
tissues. 

The  Simple  Tissues  may  be  divided  into 

1.  Cells   with    intermediate   fluid,   as  Blood,  Lymph, 
Chyle,  Mucus,  and  Pus. 

2.  Epithelium  and  its  appendages. 

3.  Connective    Substances. — Cartilage.     Fat.     Connec- 
tive tissue.     Bone.     Dentine. 

The  Compound  Tissues  are  Muscle,  Nerve,  Gland,  and 
Vascular  tissues. 

These  are  formed  into  Organs. 

1.  Vegetative. — The   Circulatory,  Respiratory,   Diges- 
tive, Urinary,  and  Generative  organs. 

2.  Animal. — The  Bony,  Muscular,  Nervous,  and  Sensory 
apparatus. 

We  shall  attempt  a  brief  description  of  these  tissues 
and  organs,  as  illustrated  by  the  microscope  and  modern 
methods  of  research. 

I.  SIMPLE   TISSUES. 
1.  CELLS  WITH  INTERMEDIATE  FLUID. 

I.   The  Blood. 

The  microscope  shows  blood  to  consist,  especially  in 
man  and  the  higher  animals,  of  red  corpuscles,  colorless 
corpuscles,  and  the  fluid  in  which  they  are  suspended. 

1.  Blood  Plasma,  or  Liquor  Sanguinis. — This  is  a  color- 
less and  apparently  structureless  fluid,  but  when  removed 
from  the  body,  fibrin  separates  from  it  in  solid  form.     In 
small  quantities  of  blood  this  is   seen  in  delicate  fibres 
crossing  each  other  at  various  angles. 

2.  Red-blood  Corpuscles. — These  were  first  discovered  by 
Swammerdam,  in  1658,  in  frog's  blood,  and  in  that  of  man 
by  Lewenhoek,  in  1673.     Malpighi  is  said  to  have  first 
seen  the  actual  circulation  of  blood  in  the  web  of  a  frog's 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          187 

foot.  The  circulation  may  be  readily  observed  by  ether- 
izing a  frog,  and  expanding  its  foot  by  means  of  pins  or 
thread,  upon  the  stage  of  the  microscope  (Plate  XVIII, 
Fig.  137).  The  circulation  may  also  be  seen  in  the  lung, 
mesentery,  or  extended  tongue,  of  the  frog. 

The  red  corpuscles  of  blood  are  flattened  disks,  which 
are  circular  in  Mammals,  except  the  camel  and  lama, 
which  have  elliptic  disks.  In  birds,  amphibia,  and  most 
fishes,  the  disks  are  elliptic.  In  a  few  fishes  (the  cyclos- 
tomata)  they  are  circular.  Their  color  depends  on  haemo- 
globulin,  which  plays  an  important  part  in  the  exchange 
of  respiratory  gases.  In  man  the  disks  are  usually  double- 
concave,  with  rounded  edges.  Out  of  the  body  they  have 
a  tendency  to  adhere,  or  run  together,  in  chains,  like  rolls 
of  coin  (Plate  XVIII,  Fig.  138).  In  the  elliptic  disks  of 
birds,  etc  ,  there  is  a  distinct  nucleus.  The  size  of  the 
disks  varies.  In  man  they  are  from  0.0045  to  0.0097  mil- 
limetre. The  smallest  disks  are  in  the  Moschus  Javanicus, 
and  the  largest  in  Siren  lacertina.  In  the  latter  they  are 
from  ^g  to  g1^  millimetre. 

It  is  estimated  that  in  a  cubic  millimetre  (about  J-§ih 
of  an  inch)  of  human  blood  there  are  5,000,000  red  cor- 
puscles, having  a  surface  of  643  millimetres. 

After  a  variable  time  from  their  removal  from  the  ves- 
sels they  suffer  contraction,  and  assume  a  stellate,  or 
mulberry  form  (Plate  XVIII,  Fig.  139).  This  occurs 
more  rapidly  in  feverish  states  of  the  system.  On  the 
warm  stage  they  suffer  still  greater  alterations.  Inden- 
tations appear,  which  cause  bead-like  projections,  some 
of  which  become  fragments,  having  molecular  motion 
(Plate  XVIII,  Fig.  139^.  The  substance  of  red  corpuscles 
is  elastic  and  extensible,  and  may  be  seen  in  the  vessels  to 
elongate  and  curve  so  as  to  adapt  themselves  to  the  calibre 
of  the  vessels. 

Electric  discharges  through  the  red  corpuscles  produce 
various  changes  of  form.  Alkalies  dissolve,  and  acids 


188  THE    MICROSCOPIST. 

cause  a  precipitate  in  them.  They  are  tinged  by  neutral 
solutions  of  carmiuate  of  ammonia.  One-half  to  1  per 
cent,  of  salt  added  to  the  staining  fluid  causes  the  nuclei 
only  of  Amphibian  corpuscles  to  be  stained.  Chloroform, 
tannin,  and  other  reagents,  produce  various  changes, 
which  suggest  a  wide  field  of  research  connected  \vith 
Therapeutics. 

The  old  opinion  of  the  structure  of  red  corpuscles  rep- 
resented them  as  vesicles  consisting  of  a  membrane  and  its 
contents,  but  Max  Schultze,  in  1861,  showed  that  a  mem- 
brane was  not  constant.  This  may  be  verified  by  break- 
ing them  under  pressure. 

Brucke's  experiment  on  the  astringent  action  of  boracic 
acid  on  the  blood  of  Triton,  repeated  by  Strieker  and  Lan- 
kester,  shows  the  red  corpuscles  to  possess  a  double  struc- 
ture. There  is  a  body,  called  (Ecoid ;  a  porous,  non-con- 
tractile, soft,  transparent  mass ;  and  a  retractile  substance, 
or  Zooid,  containing  the  hsemoglobuliu,  which  fills  the  in- 
terspaces of  the  (Ecoid.  The  Zooid  seems  identical  with 
simple  cell-substance,  or  bioplasm. 

3.  Colorless,  or  White  Corpuscles. — These  appear  to  be 
simply  masses  of  bioplasm  of  various  sizes.  Some  are 
quite  small,  and  many  are  larger  than  the  red  corpuscles. 
Their  number  is  much  smaller  than  the  red  disks,  being 
about  1  to  350,  or  even  less.  In  leucaemia  and  other  dis- 
eases their  relative  number  is  much  greater.  In  the  blood 
of  cold-blooded  animals,  and  in  that  of  vertebrata,  if  the 
normal  temperature  is  continued  by  means  of  a  warm 
stage,  the  amoeboid  motions  are  quite  perceptible  with  a 
high  magnifying  power  (Plate  XVIII,  Fig.  139).  They 
may  also  be  seen  to  take  up  small  particles  of  matter  into 
their  interior,  such  as  cinnabar,  carmine,  milk-globules, 
and  even  portions  of  the  red  globules. 

Both  red  and  white  cells  are  forced  through  the  unin- 
jured walls  of  small  vessels  by  impeded  circulation,  but 
the  white  cells  thus  migrate,  by  virtue  of  their  vital  con- 


PLATE   XVIII. 


2  V 


Capillary  circulation  in  a  portion  of  the  web  of  a  Frog's  foot. 
FIG.  138.  FIG.  139 


Alterations  in  form  in  blood-discs  : — 1,  Stellate  or  mul- 
berry form ;  2,  On  warm  stage ;  3,  Amoeboid  white-cell 
forms. 

FIG.  140. 


Blood-discs :— 1,  Eliptic  Discs  of  Amphibia ; 
2,  Human  red-corpuscles;  3,White  or  lymph- 
corpuscle  ;  4,  Rouleaux  of  red-discs. 


FIG.  141. 


Pus-corpuscles : — a,  with  acetic  acid. 
FIG.  142. 


Mucous  corpuscles  and  epithelium. 


Varieties  of  Epithelium  :— a,  Tessalated ;  b,  Squamous; 
c,  Glandular;  d,  Columnar;  e.  Ciliated. 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          189 

tractility,  in  the  healthy  body,  and  in  greater  numbers  in 
diseased  states  ;  in  some  cases  re-entering  the  lymphatic 
circulation,  and  in  others  penetrating  into  various  tissues. 
The  pus-corpuscles  appearing  in  the  vicinity  of  inflamed 
parts  are  shown  by  this  discovery,  made  by  Waller  and 
Cohnheim,  to  be  nothing  but  migratory  lymphoid  or 
white  cells  of  the  blood.  The  change  of  form  and  place 
of  these  amoeboid  cells  is  readily  seen  by  placing  a  drop  of 
frog's  blood  on  a  glass  cover,  and  inverting  it  over  a  moist 
cell.  As  it  coagulates,  a  zone  of  serum  extends  round  the 
clot,  in  which  the  migrated  cells  will  be  found. 

The  colorless  cells  originate  in  the  chyle  and  lymph- 
systems,  although  some  may  come  from  the  spleen  and 
the  medulla  of  bones,  multiplying  in  the  blood  itself,  and 
they  pass  into  red  corpuscles.  Transitional  forms  have 
been  found  in  the  general  mass  of  blood,  in  the  spleen,  and 
in  the  marrow  of  bones. 

The  white  or  colorless  cells  of  blood  are  identical  with 
the  cells  of  chyle,  lymph,  pus,  mucus,  and  saliva.  They 
are  often  described  under  the  term  leucocytes  (white  cells.) 

The  leucocytes  of  saliva  (salivary  corpuscles)  and  of  pus 
contain  granules  or  globules  of  formed  material,  which 
exhibit  for  some  time  a  peculiar  dancing  movement  (see 
page  120). 

When  at  rest,  or  in  a  lifeless  condition,  the  white  cells 
are  of  spheroidal  form,  and  generally  exhibit  granules  and 
globules  of  fat.  Acetic  acid  develops  a  nucleus,  and  some- 
times splits  it  into  several  (Plate  XVIII,  Fig.  140). 

II.  Lymph  and  Chyle. 

The  vessels  of  the  lymphatic  or  absorbent  system  re- 
ceive the  liquid  part  of  the  blood  which  has  passed  from 
the  capillaries,  together  with  the  products  of  decomposi- 
tion in  the  tissues,  and  return  them  to  the  circulation. 
The  lymphatics  of  the  intestinal  canal  receive  during 


190  THE    MICROSCOPIST. 

digestion  a  mixture  of  albuminous  and  fatty  matters, 
which  is  known  as  chyle,  and  these  vessels  have  obtained 
the  name  of  lacteals.  The  cells  in  this  fluid  are  leucocytes, 
identical  with  white  cells  in  blood.  They  originate  in  the 
lymphatic  glands  and  "  Peyer's  patches  "  of  the  intestine, 
and  are  the  corpuscles  of  these  organs  which  have  been 
carried  off  by  the  fluid  stream. 

III.  Mucus. 

Is  a  tenacious  semifluid  substance  which  covers  the 
surface  of  mucous  membranes.  It  contains  cast-off  epi- 
thelial and  gland-cells,  and  the  mucus  corpuscle,  which,  as 
we  have  before  said,  is  identical  with  other  leucocytes. 
Synovial  fluid  is  of  similar  nature.  It  is  now  regarded  as 
a  transformation  product  of  the  epithelial  cells,  and  not 
to  originate  as  a  secretion  from  special  glands  (Plate 
XVIII,  Fig.  141). 

2.  EPITHELIUM  AND  ITS  APPENDAGES. 

Epithelium  (from  e/n,  upon,  and  OaMta,  to  sprout)  is  so 
called  since  it  was  formerly  supposed  to  sprout  from  mem- 
brane. It  is  a  tissue  formed  of  cells  more  or  less  closely 
associated,  which  is  found  in  layers  upon  external  and 
internal  surfaces.  The  cells  are  generally  transparent, 
with  vesicular,  homogeneous,  or  granular  nuclei,  the  lat- 
ter being  the  remains  of  the  original  leucocyte  or  bio- 
plast. In  the  older  cells  the  nucleus  is  absent,  the  entire 
mass  having  been  transformed. 

The  forms  of  epithelial  cells  vary  according  to  situation 
or  function.  The  original  form  is  spheroidal,  but  changes 
by  compression,  etc. 

1.  Tessellated  or  pavement  epithelium  (Plate  XVIII, 
a,  Fig.  142).  These  are  cells  whose  formed  material  is 
flattened,  and  which  are  united  at  their  edges.  They  are 
sometimes  hexagonal,  and  often  polyhedral,  in  form. 

Examples :  Serous  and  synovial  membranes ;  the  pos- 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          191 

terior  layer  of  the  cornea ;  the  peritoneal  surface ;  the 
interior  of  bloodvessels,  and  shut  sacs  generally. 

2.  Squamous  or  scaly  epithelium.     The  cells  are  flat, 
and  overlap  each  other  at  the  edges  (Plate  XVIII,  6,  Fig. 
142). 

Examples :  Epidermis  ;  many  parts  of  mucous  mem- 
branes, as  the  mouth,  fundus  of  bladder,  vagina,  etc. 

3.  Glandular   epithelium  (Plate   XVIII,  c,  Fig.  142). 
The  cells  are  round  or  oval  bioplasts,  often  polyhedral 
from  pressure,  and  the  formed  material  is  often  soft. 

Examples :  Liver  cells,  convoluted  tubes  of  kidney,  and 
interior  of  glands  generally. 

4.  Columnar  epithelium  (Plate  XVIII,  d,  Fig.  142). 
Cells  cylindrical  or  oblong,  arranged  side  by  side.     A 
bird's-eye  view  shows  them  similar  to  the  tessellated  form, 
hence  they  should  be  seen  from  the  side. 

Examples :  Villi  and  follicles  of  intestine,  ducts  of 
glands,  urethra,  etc. 

Some  of  the  columnar  or  cylinder-cells  have  a  thickened 
border  or  lid  perforated  with  minute  pores  (Plate  XVIII, 
/,  Fig.  142).  They  are  found  in  the  small  intestine,  gall- 
bladder, and  biliary  ducts. 

5.  Ciliated    epithelium   (Plate    XVIII,   e,   Fig.    142). 
These  are  cylindrical  cells  having  vibratile  cilia,  whose 
motions  produce  a  current  in  the  surrounding  fluid. 

Examples:  The  upper  and  back  nasal  passages,  the 
pharynx,  bronchi,  Fallopian  tubes,  etc. 

The  Hair. — Hairs  are  filiform  appendages,  composed  of 
a  modified  epithelial  tissue  of  rather  complex  structure. 
They  originate  in  a  follicle,  which  is  a  folding  in  of  the 
skin.  The  shaft  of  the  hair  is  the  portion  projecting 
above  the  skin,  and  the  root  is  concealed  in  the  hair-fol- 
licle. The  bulb  of  the  root  is  the  rounded  terminal  part, 
which  is  hollow  below,  and  rests  on  a  papilla  which  rises 
from  the  floor  of  the  follicle  (Plate  XIX,  Fig.  143).  Be- 
tween the  follicle  and  hair  is  a  sheath,  which  is  divided 


192  THE    MICROSCOPIST. 

into  an  external  and  internal  portion.  The  cells  of  the 
hair  may  be  isolated  by  sulphuric  acid  or  solution  of  soda. 
They  overlap  each  other  like  tiles,  so  as  to  present  undu- 
lating or  jagged  lines  across  the  surface  of  a  fresh  hair. 
The  felting  property  of  wool  depends  on  the  looseness  of 
this  overlapping.  Air-bubbles  are  often  found  in  hair, 
especially  in  the  medullary  or  axial  portion,  and  give  a 
silvery  appearance  to  white  hair.  The  granules  of  pig- 
ment are  generally  found  in  the  cortical  portion. 

Nails  are  nothing  more  than  modified  cuticle,  depen- 
dent for  their  growth  on  the  vessels  of  the  matrix  or  bed 
of  the  nail.  Their  epithelial  cells  may  be  demonstrated 
by  soaking  in  caustic  soda  or  potash. 

Corns,  icarts,  and  horn  have  similar  origin. 

Enamel  of  the  Teeth. — The  minute  structure  of  dental 
tissue  will  be  described  hereafter,  but  as  the  enamel  is 
generally  considered  to  be  of  epithelial  origin,  some  ac- 
count of  it  belongs  here.  .  . 

O 

The  edge  of  the  jaw  is  first  marked  by  a  slight  groove, 
known  as  the  dental  groove,  and  is  covered  with  a  thick 
ridge  of  epithelium,  called  the  dental  ridge  (Plate  XIX, 
Fig.  144,  1  a,  2  a).  The  epithelium  grows  down  in  a 
process  which  has  been  called  the  enamel  germ  (1  d). 
This  becomes  doubled  by  the  upward  growth  of  the 
dental  germ  (2,  3,/),  which  originates  from  connective 
tissue.  The  epithelial  cells  become  transformed  into 
enamel  columns  or  prisms. 

3.  CONNECTIVE  SUBSTANCES  OR  TISSUES. 

The  term  connective  tissue  has  been  given  to  a  variety 
of  structures  which  probably  start  from  the  same  rudi- 
ments, and  have  a  near  connection  with  each  other.  It 
is  unfortunate  that  a  name  descriptive  of  function  should 
be  applied  to  structure,  yet  the  present  state  of  histology 
requires  an  account  of  substances  thus  called. 

Connective  tissues  are  all  those  which  may  be  regarded 


PLATE  XIX. 


FIG.  143. 


Connective-tissue  elements.  From  the  Frog's  Thigh  :— 
a,  contracted  cell;  ft,  ramified  ;  c,  fl,  motionless  gran- 
ular cells;  /,  fibrillse;  g,  connective-tissue  bundle; 
h,  elastic  fibre  net-work. 


Development  of  the  enamel: — a,  dental  ridge 
6,  young  layer  of  epithelium;  c,  deep  layer;  d 
enamel  germ  ;  e,  enamel  organ  ;  /,  dental  germ. 


FIG.  146. 


White  Fibrous  Tissue,  from  Ligament. 


FIG.  147. 


Yellow  Fibrous  Tissue,  from  Ligamentum  Nuchse 
of  Calf. 


FIG.  148. 


Fatty  Tissue. 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          193 

as  basement-membranes,  supporting  layers  or  investments 
for  epithelial  structures,  blood,  lymph,  muscle,  and  nerves,. 
It  includes  ordinary  connective  tissue  (white  and  yellow 
fibrous  tissues),  cartilage,  bone,  corneal  tissue,  dentine,, 
and  fatty  tissue. 

Most  of  the  difficulty  found  in  the  consideration  of 
these  tissues  arises  from  discussions  relative  to  the  inter- 
cellular substance.  Max  Schultze  and  Beale  agree  in  re^ 
garding  it  to  originate  from  the  protoplasm  or  bioplasm 
of  cells. 

The  cells  are,  according  to  Frey,  originally  spheroidal, 
with  vesicular  nuclei,  and  between  them  is  an  albuminous 
intercellular  substance — a  product  of  the  cells,  or  trans- 
formed cells— which  usually  undergoes  fibrillation,  while 
the  cells  become  stunted,  or  develop  into  spindle-shaped 
or  stellate  elements.  Calcification  of  the  intercellular  sub- 
stance occurs  in  some  of  these  tissues,  as  bone  and  dentine. 

The  cells  of  connective  tissue  present  many  varieties. 
Eecklinghausen  first  observed  migrating  lymphoid  cells 
or  bioplasts  in  the  cornea  of  the  eye,  the  tail  of  the  tad- 
pole, the  peritoneum,  and  in  various  other  places.  The- 
exit  of  white  corpuscles  from  the  vascular  walls  renders 
it  probable  that  these  amoeboid  cells  originate  in  the  blood. 
Granular  cells,  of  various  forms — rounded,  fusiform,  and 
stellate — are  also  observed.  Some  of  the  stellate  cells 
give  off  anastomosing  branches.  Pigment  cells,  filled  with 
granular  pigment,  are  also  met  with  (Plate  XIX,  Fig. 
145). 

In  its  earliest  stages,  connective  tissue  consists  of  closely- 
compressed  cells,  but  in  the  adult  two  principal  forms 
have  been  distinguished ;  first,  those  networks  and  trabec- 
ulse,  developed  from  cells,  which  do  not  yield  gelatin  on 
boiling,  and,  secondly,  fibrillar  connective  tissue  composed 
of  a  gelatin-yielding  substance.  Of  the  first  kind  we  notice 
the  following  varieties : 

1.  Independent  masses  of  gelatinous  or  mucous  tissue, 

13 


194  THE    MICROSCOPIST. 

oonsisting  of  nucleated  cells,  giving  off  smooth  anasto- 
mosing trabeculae,  as  in  the  early  stage  of  the  vitreous 
humor  of  the  eye  and  of  the  gelatinous  tissue  of  the  um- 
bilical cord,  etc. 

2.  Very  delicate  reticular  tissue  found  in  the  eye  and  in 
the  interior  of  nerve-centres. 

3.  A  network  filled   with  lymphoid  cells  (adenoid  or 
cytogenous  tissue)  in  the  glands  of  the  lymphatic  system, 
and  around  the  fasciculi  of  fibrillar  connective  tissue. 

4.  A  coarser  network  in  the  ligamentum   pectinatum 
of  the  human  eye. 

5.  A  tissue  formed  of  fusiform  and  stellate  cells,  as  in 
the  interior  of  the  kidneys 

The  second  form  referred  to,  or  the  fibrillar  connective 
tissue,  was  the  only  form  to  which  the  term  connective 
tissue  was  formerly  applied.  It  is  composed  of  gelatin- 
yielding  fibrillae,  which  may  be  split  into  skein-like  por- 
tions of  various  breadth.  (Plate  XIX,  Fig.  146.)  Per- 
manganate of  potash  stains  it  brown.  Acetic  and  dilute 
mineral  acids  cause  the  tissue  to  swell  so  that  the  appear- 
ance of  fibrillation  is  lost  through  compression,  and  the 
cells,  or  nuclei,  are  made  manifest.  Chloride  of  gold 
staining  exhibits  both  fibrillae  and  cells. 

Elastic  fibres  (yellow  elastic)  (Plate  XIX,  Fig.  147)  are 
apparent  in  all  forms  of  connective  tissue  which  have  been 
made  transparent  by  boiling,  or  acetic  acid.  They  are 
non-gelatinizing,  cylindric,  slightly  branched,  or  forming 
plexuses.  In  some  fasciculi  of  fibrillar  connective  tissue,  as 
seen  after  the  action  of  acetic  acid,  elastic  fibres  appear  in 
hoops,  or  spirals,  around  them.  In  the  ligamentum  nu- 
cleae  of  the  giraffe  the  elastic  fibres  are  marked  by  trans- 
verse striae,  or  cracks.  Elastic  fibres  often  form  flattened 
trabeculse,  or  are  fused  into  elastic  plates,  or  membranes, 
with  foraminae.  as  in  arterial  tunics. 

The  ligaments  of  the  skeleton,  the  periosteum,  peri- 
chondrium,  aponeuroses,  fasciae,  tendons,  and  generally  all 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.  195 

the  tunics  of  the  body,  afford  examples  of  the  fibrillar 
connective  tissue. 

Fatty  Tissue. — The  loose  connective  tissue  contains  in 
various  parts  great  numbers  of  cells  filled  with  fat.  Their 
form  is  round,  or  oval,  and  are  often  divided  into  groups, 
or  lobules,  by  trabeculse.  (Plate  XIX,  Fig.  148.)  Each 
lobule  has  its  own  system  of  bloodvessels,  which  divide 
into  such  numerous  capillaries  that  the  smaller  groups, 
and  even  individual  fat-cells,  are  surrounded  by  vascular 
loops.  Sometimes  the  contents  of  the  cells  appear  in 
needle-shaped  crystals,  often  collected  in  a  brush-like  form. 
Fat-cells  seem  to  be  chiefly  receptacles  for  the  deposit  of 
superabundant  oleaginous  nutriment,  and  are  analogous 
to  the  starch-cells  in  vegetables. 

Cartilage. — This  is  formed  of  cells  in  an  originally  homo- 
geneous intercellular  substance.  The  only  difference  be- 
tween what  was  formerly  distinguished  as  cartilage  and 
fibre-cartilage  is  that  the  matrix  or  intercellular  substance 
of  the  latter  is  fibrous. 

The  cells,  or  cartilage-corpuscles,  are  nucleated,  and  lie 
in  cavities  of  various  sizes  and  form  in  the  matrix  (Plate 
XX,  Fig.  149).  Two  nuclei  often  appear  in  one  cell.  It 
is  yet  a  question  whether  the  capsule  and  matrix  are  the 
secretion  of  the  cells  which  has  become  solid,  or  a  part  of 
the  body  of  the  cell  which  has  undergone  metamorphosis. 

The  multiplication  of  cartilage-cells  is  endogenous.  By 
segmentation,  two,  four,  or  a  whole  generation  of  daughter- 
cells,  so  called,  may  lie  in  the  interior  of  a  capsule.  In  this 
way  growing  cartilage  may  acquire  a  great  number  of 
elements. 

In  the  ear  of  the  mouse,  etc.,  we  observe  a  form  of  car- 
tilage which  is  wholly  cellular,  and  possesses  no  matrix 
(Plate  XX,  Fig.  150). 

Bone,  or  osseous  tissue,  is  formed  secondarily  from  meta- 
morphosed descendants  of  cartilage  or  connective-tissue 
cells,  and  is  the  most  complex  structure  of  this  group.  It 


196  THE    MICROSCOPIST. 

consists  essentially  of  stellate  ramifying  spaces  containing 
cells,  and  a  hard,  solid,  intermediate  substance.  The  latter 
is  composed  of  glutinous  material  rendered  hard  by  a  mix- 
ture of  inorganic  salts,  chiefly  of  calcium. 

As  all  bones  are  moulded  first  in  cartilage  it  was  natural 
to  conceive  that  they  were  developed  by  a  transformation 
of  cartilage.  Much  variety  of  opinion  still  exists  respect- 
ing the  process,  but  it  is  generally  conceded  that  although 
cartilage  may  undergo  calcification,  true  bone  is  not  formed 
ia.ntil  the  cartilage  is  dissolved.  Kew  generations  of  stel- 
late cells  appear  in  a  matrix,  which  is  first  soft  and  then 
calcified.  New  bone  may  also  grow  from  the  periosteum 
by  means  of  a  stratum  of  cells  called  osteoblasts.  The  de- 
tails of  the  process  are  too  extensive  for  a  treatise  like  the 
present.  If  sections  of  growing  bone  are  decalcified  with 
chromic  acid  and  treated  with  carmine,  the  osteoblastic 
layers  and  adjacent  youngest  bony  layer  acquire  an  in- 
tensely red  color,  while  the  rest  of  the  tissue,  except  the 
bone-corpuscles,  remains  uncolored. 

Fine  sections  cut  from  a  long  bone  longitudinally  and 
transversely  will  show  the  microscopic  structure,  consist- 
ing of  the  Haver sian  canals  (Plate  XX,  Fig.  151,  a)  sur- 
rounded with  concentric  lamellae  of  compact  structure  (6,  b). 
There  are  also  intermediate  and  periosteal  lamellae  (c,  d). 
The  cavities  containing  the  bone-cells,  or  bioplasts  (e,  e,) 
are  of  various  sizes,  from  0.0181  to  0.0514  millimetres 
long,  and  from  these  lacunae  run  the  canaliculi  in  an  irregu- 
lar radiating  course  (/,/).  In  a  balsam-mounted  specimen 
these  hollows  sometimes  retain  air,  by  which  the  structure 
is  rendered  more  apparent. 

Dentine  is  the  structure  of  which  the  teeth  are  most 
largely  composed.  It  consists  of  minute  tubes  filled  with 
bioplasm,  which  radiate  from  the  central  cavity  of  the 
tooth,  the  interspaces  between  the  tubes  being  solidified 
by  earthy  salts  so  that  the  tissue  is  harder  than  bone. 

Histologically  a  tooth  may  be  said  to  be  made  of  three 


PLATE 


FIG.  149. 


.  150. 


Cellular  Cartilage  of  Mouse's  Ear. 


Section  of  the  Branchial  Cartilage  of  Tadpole. 


FIG.  151. 


Longitudinal  and  transverse  section  of  Bone: — a,  Haver- 
sian  canals;  ft,  concentric  lamellae;  c,  intermediate;  d, 
periostial  lamellae;  e,  bone-cells;  /,  canaliculi. 


FIG. 152. 


FIG.  153. 


Vertical  section  of  Human 
Molar  Tooth: — 1,  enamel;  2, 
cementumor  crustapetrosa  ; 
3,  dentine,  or  ivory  ;  4,  osse- 
ous exere9cence,arising  from 
hypertrophy  of  cementura  ; 
5,  pulp-cavity;  6,  osseous 
lacunae  at  outer  part  of  den- 
tine. 


FIG.  154. 


Striated  Muscular-fibre,  separated  into  fibrillue 


Involuntary  Muscular-fibre. 


Sarcolemma. 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.         197 

kinds  of  tissue:  the  cement,  a  bony  substance,  coating  the 
root  of  the  tooth,  containing  bone-cells  and  canaliculi,  but 
no  Haversian  canals,  the  pulp  in  the  central  cavity  of  the 
tooth  serving  for  the  nutrition  of  the  organ,  as  a  large 
Haversian  canal ;  the  dentine,  or  ivory,  constructed  as 
above  described;  and  the  enamel, covering  the  crown, arid 
consisting  of  columns  or  prisms,  often  hexagonal,  which 
are  the  hardest  and  densest  structures  of  the  body  (Plate 
XX,  Fig.  152). 

The  development  of  enamel  from  epithelium  has  been; 
referred  to  on  page  192.  The  dental  germ  corresponds  to' 
a  papilla  of  the  mucous  membrane,  and  in  an  early  stage 
is  covered  by  delicate  stratified  cells — the  dentine  cells, 
or  odontoblasts — which  produce  dentine.  Teeth  are  thus 
produced  abnormally  in  other  situations  besides  the  jaws, 
as  in  ovarian  cysts,  etc. 

Before  the  development  of  the  first,  or  milk  teeth,  the 
rudiments  of  the  permanent  teeth  exist  as  a  fold  or  leaf 
of  epithelium  springing  from  the  enamel  germ, 

II.  COMPOUND  TISSUES, 

1.  Muscle. — This  is  the  tissue  by  which  the  principal 
movements  of  the  body  are  performed.  It  consists  of 
fibrin,  which  is  endowed  with  special  contractile  power. 
It  is  of  two  kinds,  the  voluntary,  pertaining  to  organs  of 
voluntary  motion,  and  the  involuntary,  found  in  situa- 
tions which  are  not  under  the  control  of  volition,  as  the 
coats  of  bloodvessels,  alimentary  canal,  uterus,  and  blad- 
der. The  fibres  of  voluntary  muscles  are  marked  with 
transverse  stride.  Involuntary  muscular  fibres  are  smooth, 
except  in  a  few  instances,  as  the  fibres  of  the  heart  and 
some  of  those  in  the  oesophagus,  which  are  striated. 

The  fibres  are  connected  with  and  invested  by  connec- 
tive tissue,  and  arranged  in  parallel  sets,  with  vessels  and 
nerves  in  the  intervals,  and  are  attached  to  the  parts  they 


198  THE    MICROSCOPIST. 

are  designed  to  move  by  tendon,  aponeuroses,  or  some  form 
of  fibrous  tissue.  The  organs  or  muscles  thus  formed  are 
generally  solid  and  elongated,  but  sometimes  expanded. 

Involuntary  or  unstriped  muscular  fibres  are  flat  bands 
or  spindle-shaped  fibres  with  nuclei,  which  may  be  re- 
garded as  the  remains  of  the  formative  bioplasm  (Plate 
XX,  Fig.  153).  They  are  usually  transverse,  or  interlace 
with  each  other  on  the  walls  of  cavities  and  vessels.  In 
the  heart  the  fibres,  though  involuntary,  are  striped  and 
branching.  Striped  fibre  varies  from  ^th  to  y^th  inch 
in  diameter.  It  is  largest  in  insects,  in  which  individual 
fibrils  may  be  readily  obtained,  especially  from  the  thoracic 
muscles.  They  are  generally  found  in  bundles  of  fibrils, 
splitting  longitudinally  or  in  disks,  and  each  bundle  is 
inclosed  in  a  sheath  or  sarcolemma  (Plate  XX,  Fig.  154). 

The  transverse  striation  of  muscle  is  subject  to  much 
variation,  and  the  precise  nature  of  the  sarcous  elements 
which  produce  the  appearance  is  yet  a  matter  of  dispute, 
but  in  all  probability  the  ultimate  elements  are  sarcous 
prisms  or  particles  imbedded  in  a  homogeneous  mass,  and 
by  their  mutual  attraction,  excited  by  various  stimuli, 
the  contraction  of  the  fibre  takes  place. 

For  the  purpose  of  observation,  the  connective  tissue 
may  be  removed  from  muscular  fibre  by  gelatinizing  it 
with  dilute  sulphuric  acid,  and  dissolving  it  at  a  temper- 
ature of  104°  F.  The  nuclei  of  muscular  fibre  are  seen 
after  treating  with  acetic  acid,  and  may  be  stained  with 
carmine  fluid,  etc. 

2.  Nerve-tissue. — The  term  nerve  was  applied  by  the 
ancients  to  tense  cords,  as  bow-strings,  musical  strings, 
etc.,  and  was  appropriated  to  the  fibres  now  called  nerves, 
because  they  deemed  them  to  operate  by  tremors,  vibra- 
tions, or  oscillations,  another  instance  of  wrong  naming 
of  structure  from  an  opinion  respecting  function.  Hip- 
pocrates, Galen,  and  others,  however,  thought  nerves  were 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          199 

hollow  tubes,  conveying  fine  ethereal  fluids,  termed  ani- 
mal spirits. 

Nervous  matter  is  soft,  unctuous,  and  easily  disturbed, 
hence  it  is  necessary  to  examine  it  while  fresh.  Histo- 
logically  it  is  divided  into  fibres  and  cells,  imbedded  in 
connective  tissue. 

Nerve-fibres  are  of  two  kinds,  the  medullated,  or  dark- 
bordered  threads,  and  the  pale,  or  non-rnedullated.  Med- 
ullated fibres  consist  of  a  delicate  envelope  of  connective 
tissue,  called  the  neurilemma  or  primitive  sheath,  an  axis- 
cylinder  or  albuminous  portion,  extending  down  the  cen- 
tre, and  a  portion  composed  of  a  mixture  of  albumen, 
cerebral  matter,  and  fat,  surrounding  the  axis-cylinder 
(Plate  XXI,  Fig.  155,  A,  B,  c).  This  latter  is  the  medul- 
lary sheath,  or  white  substance  of  Schwann.  It  changes 
rapidly,  so  as  to  coagulate  and  become  granular.  Alka- 
lies render  it  fluid,  so  as  to  exude  in  fat-like  drops.  Ab- 
solute alcohol,  chromate  of  potass  and  collodion,  contract 
the  sheath,  so  as  to  permit  the  axis-cylinder,  which  is  the 
essential  part  of  the  nerve,  to  protrude  (Plate  XXI,  E, 
Fig.  155).  Anilin,  carmine,  nitrate  of  silver,  and  chloride 
of  gold  stain  the  axis,  while  osmic  acid  blackens  only  the 
medullary  sheath. 

Non-medullary  or  pale  nerve-fibres  are  regarded  as  em- 
bryonic or  developmental  forms  (Plate  XXI,  D,  Fig.  155). 
The  ganglionic  fibres  of  the  sympathetic  (Remak's  fibres) 
are  flat,  homogeneous  bands,  with  round  or  oval  nuclei. 
Some  have  considered  them  as  formed  of  connective  tis- 
sue, but  their  nervous  character  is  generally  conceded. 

Schultze  and  others  regard  the  axis-cylinder  as  made  up 
of  extremely  delicate  fibrillas. 

Nerve-cells,  or  ganglion  corpuscles,  are  of  two  kinds, 
those  without  and  those  with  processes.  The  first  are 
called  apolar,  and  the  latter  unipolar,  bipolar,  or  multi- 
polar,  according  to  the  number  of  ramifications.  The 
cells  are  nucleated,  and  inside  the  nucleus  is  usually 


•200  THE    MICROSCOPIST. 

another,  the  nucleolus.  Dr.  Beale  discovered  certain  gan- 
glion-cells in  the  sympathetic  of  the  tree-frog  (in  the  au- 
ricular septum  of  the  heart),  one  of  whose  poles  is  encir- 
cled spirally  by  the  others  (Plate  XXI,  Fig.  156). 

The  ultimate  structure  of  ganglia  or  nervous  knots, 
and  the  relation  of  the  fibres  to  the  cells,  opens  a  wide 
field  of  research.  In  the  muscle  of  the  heart,  etc.,  many 
of  these  ganglia  seem  to  form  special  nervous  systems. 
Dr.  Beale  has  described  the  nerves  ramifying  on  the  capil- 
laries and  involuntary  muscular  fibrils  of  the  terminal  ar- 
teries as  a  self-regulating  mechanism  for  the  distribution 
of  blood  (Plate  XXI,  Fig.  157).  Thus,  if  a  tissue  receives 
excess  of  pabulum,  the  capillary  nerve-fibre  is  disturbed 
and  transmits  a  change  to  the  ganglion,  and  thence 
through  the  efferent  nerve  to  the  muscular  fibres  of  the 
artery,  and  vice  versa. 

Meissner  has  shown  many  ganglionic  plexuses  in  the 
submucous  coat  of  the  alimentary  canal.  Another  system 
of  the  same  kind,  called  the  plexus  myentericus,  was  dis- 
covered by  Auerbach  between  the  muscular  layers  of  the 
intestinal  tube.  Similar  plexuses  exist  in  other  organs. 

As  to  the  peripheral  termination  of  nerve-fibres,  there 
is  still  considerable  discussion.  Most  of  the  German  his- 
tologists  consider  the  nerves  of  voluntary  muscles  to  ter- 
minate in  end  plates,  in  which  the  neurilemma  becomes 
continuous  with  the  sarcolemma  of  the  muscular  fibre. 
Dr.  Beale  maintains  that  there  is  a  plexus  of  minute  nerves 
over  the  fibrils.  In  some  of  my  own  preparations,  espe- 
cially some  stained  with  soluble  Prussian  blue,  a  disk 
formed  of  a  plexus  of  excessively  minute  nerve-fibres  is 
observed,  from  which  tortuous  branches  go  to  other  mus- 
cle-fibres. 

In  the  cornea,  Cohnheim  and  Klein  have  traced  fine 
nerve-fibres  to  the  epithelial  cells  of  the  conjunctiva,  by 
means  of  chloride  of  gold  staining. 

3.  Glandular  tissue  consists  of  a  fine  transparent  mem- 


PLATE  XXI. 


FIG. 155. 


FIG. 156. 


Various  Ganglionic  Nerve-cells. 


Self-regulating  System  of  Ganglia — nerv 
arteries,  and  capillaries. 


Glandular  Tissue. 


FIG.  160 


Layers  of  Blastoderm. 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          201 

brane,  through  which  the  plasma  transudes,  and  cells  of 
glandular  epithelium.  A  vascular  network  exists  on  the 
surface  of  the  membrane,  from  which  the  material  of  the 
secretion  is  obtained.  This  membrane  may  be  a  simple 
follicle,  or  tube,  as  in  the  mucous  membrane,  or  system  of 
tubes,  as  in  the  kidneys,  a  convoluted  tube,  a  simple  open 
vesicle,  a  racemose  aggregation  of  vesicles,  or  a  close  cap- 
sule which  discharges  itself  by  bursting.  (Plate  XXI, 
Fig.  158). 

4.  Vascular  Tissue. — The  smallest  bloodvessels  and  lym- 
phatics, called  capillaries,  are  minute  tubes,  consisting  of  a 
series  of  flattened  epithelial  cells,  and  containing  stomata, 
or  openings  through  which  white  or  red  blood-corpuscles 
may  occasionally  pass  (Plate  XX,  Fig.  159,  a,  b).  The 
larger  trunks  have,  in  addition  to  the  cellular  layer,  one 
of  longitudinally  striated  connective  tissue,  a  middle  coat 
containing  transverse  muscular  fibres,  and  an  external  coat 
of  connective  tissue  (Plate  XXI,  Fig.  159).  The  distribu- 
tion of  the  capillary  bloodvessels  is  various,  according  to 
the  nature  or  function  of  the  organ  or  tissue  in  which  they 
are  found. 

DEVELOPMENT  or  THE  TISSUES. 

It  has  been  stated,  page  125,  that  reproduction  in  the 
higher  animals  consists  of  an  ovum  fecundated  by  contact 
with  a  sperm-cell,  or  spermatozoid.  The  ovum  consists 
of  a  germinal  vesicle,  containing  one  or  more  germinal  spots, 
and  included  within  a  vitellus  (a  yelk)  which  is  surrounded 
by  avitdline  membrane,  which  may  have  additional  invest- 
ments in  the  form  of  layers  of  albumen  and  of  an  outer 
coriaceous  or  calcified  shell. 

.The  first  step  in  the  development  of  the  embryo  is  the 
division  of  the  vitelline  substance  into  cleavage-masses,  at 
first  two,  then  four,  then  eight,  etc.  This  process  of  yelk- 
division  may  affect  the  whole  yelk  or  a  part  of  it,  and  re- 
sults in  the  formation  of  a  blastoderm,  or  embryogenic 


202  THE    MICROSCOPIST. 

tissue.  This  rudimentary  embryonic  tissue  consists  of 
three  layers  of  cells,  or  germinal  plates.  The  upper  is  the 
corneous  layer,  or  epiblast,  the  middle  one  the  intermediate 
plate,  or  mesohlast,  and  the  lower  the  intestinal  glandular 
layer,  or  hypoblast  (Plate  XXI,  Fig.  160).  From  these 
the  various  tissues  and  organs  are  developed. 

The  outer  plate  produces  the  epithelium  of  the  skin  and 
its  appendages,  with  the  cellular  elements  of  the  glands  of 
the  skin,  mammae,  and  lachrymal  organs.  By  a  peculiar 
folding  over  the  axis  this  plate  also  produces  the  elements 
of  the  brain  and  spinal  cord,  and  the  internal  parts  of  the 
organs  of  special  sense.  The  physiological  significance  of 
this  layer  is,  therefore,  very  great. 

The  lower  stratum  of  the  blastoderm  supplies  the  epi- 
thelium of  the  digestive  tract,  and  the  cellular  constituents 
of  its  various  glands,  together  with  the  liver,  lungs,  and 
pancreas. 

The  middle  layer  supplies  the  material  for  many  struc- 
tures. The  whole  group  of  connective  substances,  or 
tissues  of  support;  muscular  tissue;  blood  and  lymph, 
with  their  containing  vessels  ;  lymph-glands,  including 
the  spleen,  etc.,  all  arise  from  this.  The  epithelial  cells 
of  such  tubes  and  cavities  as  originate  in  this  layer  are 
regarded  as  different  from  those  of  true  glands,  and  are 
more  permeable  to  fluids.  They  have  been,  termed  false 
epithelium,  or  endothelium. 

The  following  description,  by  Professor  Huxley,  will 
enable  the  student  to  form  an  idea  of  the  general  process 
of  development.  A  linear  depression,  the  primitive  groove, 
makes  its  appearance  on  the  surface  of  the  blastoderm, 
and  the  substance  of  the  mesoblast  along  each  side  of  this 
groove  grows  up,  carrying  with  it  the  superjacent  epiblast. 
Thus  are  produced  the  two  dorsal  lamince,  the  free  edges 
of  which  arch  over  toward  one  another,  and  eventually 
unite,  so  as  to  convert  the  primitive  groove  into  the  cere- 
bro-spinal  canal.  The  portion  of  the  epiblast  which  lines 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          203 

this,  cut  off  from  the  rest,  becomes  thickened,  and  takes 
on  the  structure  of  the  brain,  or  encephalon,  in  the  region 
of  the  head;  and  of  the  spinal  cord,  or  myelon,  in  the 
region  of  the  spine.  The  rest  of  the  epiblast  is  converted 
into  the  epidermis. 

The  part  of  the  blastoderm  which  lies  external  to  the 
dorsal  laminae  forms  the  ventral  lamince  ;  and  these  bend 
downward  and  inward,  at  a  short  distance  on  either  side 
of  the  dorsal  tube,  to  become  the  walls  of  a  ventral  or 
visceral  tube.  The  ventral  laminae  carry  the  epiblast  on 
their  outer  surfaces,  and  the  hypoblast  on  their  inner  sur- 
faces, and  thus,  in  most  cases,  tend  to  constrict  off  the 
central  from  the  peripheral  portions  of  the  blastoderm. 
The  latter,  extending  over  the  yelk,  incloses  it  in  a  kind 
of  bag.  This  bag  is  the  first  formed  and  the  most  con- 
stant of  the  temporary,  or  foetal  appendages  of  the  young 
vertebrate,  the  umbilical  vesicle. 

While  these  changes  are  occurring,  the  mesoblast  splits, 
throughout  the  regions  of  the  thorax  and  abdomen,  from 
its  ventral  margin,  nearly  up  to  the  notochord  (which  has 
been  developed,  in  the  meanwhile,  by  histological  differen- 
tiation of  the  axial  indifferent  tissue,  immediately  under 
the  floor  of  the  primitive  groove)  into  two  lamellae.  One 
of  these,  the  visceral  lamella,  remains  closely  adherent  to 
the  hypoblast,  forming  with  it  the  splanchnopleure,  and 
eventually  becomes  the  proper  wall  of  the  enteric  canal ; 
while  the  other,  the  parietal  lamella,  follows  the  epiblast, 
forming  with  it  the  somatopleure,  which  is  converted  into 
the  parietes  of  the  thorax  and  abdomen.  The  point  of 
the  middle  line  of  the  abdomen  at  which  the  somato- 
pleures  eventually  unite,  is  the  'umbilicus. 

The  walls  of  the  cavity  formed  by  the  splitting  of  the 
ventral  laminae  acquire  an  epithelial  lining,  and  become 
the  great  pleuroperitoneal  serous  membranes  (Huxley's 
Anatomy  of  Vertebrated  Animals). 

In  addition  to  the  umbilical  vesicle,  above  described  as 


204  THE    MICROSCOPIST. 

a  temporary  appendage,  the  foetus  has  other  special  struc- 
tures, derived  from  the  blastoderm.  Thus  the  somato- 
pleure  grows  up  over  the  embryo  arid  forms  a  sac  filled 
with  clear  fluid,  the  amnion.  The  outer  layer  of  the  sac 
coalesces  with  the  vitelline  membrane  to  form  the  chorion. 
The  atlantois  begins  as  an  outgrowth  from  the  mesoblast. 
It  becomes  a  vesicle,  and  receives  the  ducts  of  the  primor- 
dial kidneys  or  Wolffian  bodies,  and  is  supplied  with  blood 
from  the  two  hypogastric  arteries  which  spring  from  the 
aorta.  The  allantois  is  afterwards  cast  off  by  the  contrac- 
tion of  its  pedicle;  but  a  part  of  its  root  is  usually  re- 
tained, and  becomes  the  permanent  urinary  bladder.  In 
the  Mammalia  the  allantois  conveys  the  embryonic  ves- 
sels to  the  internal  surface  of  the  chorion,  whence  they 
draw  supplies  from  the  vascular  lining  of  the  uterus. 

Foster  and  Balfour  recommend  that  the  study  of  em- 
bryonic development  should  commence  with  the  egg  of  a 
fowl  taken  at  different  times  from  a  brooding  hen,  or  an 
artificial  incubator.  The  egg  should  be  placed  on  a  hol- 
low mould  of  lead  in  a  basin,  and  covered  with  a  warm 
solution  of  salt  (7.5  per  cent.).  It  should  be  opened  with 
a  blow,  or  by  filing  the  shell.  "With  the  naked  eye  or 
simple  lens,  lying  across  the  long  axis  of  the  egg,  may  be 
seen  the  pellucid  area,  in  which  the  embryo  appears  as  a 
white  streak.  The  mottled  vascular  area,  with  the  blood- 
vessels, and  the  opaque  area  spreading  over  the  yelk,  may 
be  observed.  The  blastoderm  may  be  cut  out  with  a  sharp 
pair  of  fine  scissors,  floated  into  a  watch-glass,  freed  from 
vitelline  membrane  and  yelk,  and  removed  (under  the  salt 
solution)  to  a  glass  slide.  A  thin  ring  of  putty  may  then 
be  placed  round  the  blastoderm,  which  is  covered  with 
salt  solution,  and  the  thin  glass  cover  put  on.  With  a 
low-power  objective  many  of  the  details  of  structure  may 
be  seen  in  an  embryo  of  thirty-six  to  forty-eight  hours 
incubation,  as  the  heart,  the  neural  tube,  the  first  cere- 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          205 

bral  vesicles,  the  folds  of  the  somatopleure  and  splanch- 
nopleure,  the  provertebrre,  etc. 

To  prepare  sections  of  the  embryo,  it  must  be  first  hard- 
ened by  placing  the  slide  containing  it  in  a  solution  of  1 
per  cent,  chromic  acid  for  twenty-four  hours.  From  this 
it  should  be  removed  to  one  of  3  per  cent,  for  twenty-four 
hours  more  ;  then  for  a  similar  time  in  alcohol  of  70  per 
cent.,  then  in  alcohol  of  90  per  cent.,  and  lastly  in  abso- 
lute alcohol,  where  it  may  remain  till  required  for  section. 
Sometimes  picric  or  osmic  acid  is  used  for  hardening. 
The  embryo  may  be  stained  by  placing  it  in  Beale's  car- 
mine fluid  for  twenty-four  hours,  and  then  replacing  it  in 
absolute  alcohol  for  a  day  before  it  is  cut.  It  may  also 
be  stained  with  hsematoxylin  if  preferred.  The  specimen 
may  be  imbedded  in  paraffin,  wax,  and  oil,  or  a  mixture 
of  four  parts  of  spermaceti  to  one  part  of  cocoa  butter  or 
castor  oil.  If  there  are  cavities  in  the  object,  it  is  best 
to  saturate  it  first  with  oil  of  bergamot.  A  little  melted 
spermaceti  mixture  is  poured  on  the  bottom  of  a  small 
paper  box,  and  when  solid  the  embryo  is  placed  flat  on 
it,  the  superfluous  oil  removed  as  far  as  possible,  and  the 
warm  mixture  poured  on.  Bubbles  can  be  removed  with 
a  hot  needle.  A  mark  should  be  made  of  the  exact  posi- 
tion of  the  embryo.  Sections  may  be  cut  with  the  sec- 
tion-cutter or  a  sharp  razor,  and  if  the  spermaceti  mix- 
ture is  used,  the  razor  should  be  moistened  with  olive  oil. 
The  sections  should  be  floated  from  the  razor  to  the  slide, 
and  treated  with  a  mixture  of  four  parts  turpentine  and 
one  of  creasote.  They  may  then  be  mounted  in  balsam 
or  dammar  varnish. 

The  most  instructive  transverse  sections  of  an  early 
embryo  will  be  through  the  optic  vesicles,  the  hind  brain, 
the  middle  of  the  heart,  the  point  of  divergence  of  the 
splanchnopleure  folds,  the  dorsal  region,  and  a  point  where 
the  medullary  canal  is  still  open.  For  the  unincubated 
blastoderm  only  one  section,  through  the  centre,  is  re- 


206  THE    MICROSCOPIST. 

quired1  to  show  the  formative  layers.  In  the  later  stages 
dissection  is  required,  and  is  best  performed  with  embryo 
preserved  in  spirit.  If  living  embryos  are  placed  in  spirit, 
a  natural  injection  of  the  vessels  may  be  obtained. 

III.  ORGANS  OF  THE  BODY. 

Anatomists  usually  group  the  organs  into  systems,  as 
the  osseous,  muscular,  nervous,  vascular  systems,  etc.,  but 
for  histological  study  a  classification  based  on  physiologi- 
cal considerations  may  be  more  convenient  for  the  student. 

I.  VEGETATIVE  ORGANS. 

1.  Nutritive,  or  organs  pertaining  to  the  absorption  and 
distribution  of  pabulum,  including  the  digestive  and  cir- 
culatory organs. 

The  mucous  membrane  of  the  intestinal  canal  contains 
many  follicles  and  glands,  whose  secretions  serve  impor- 
tant offices  iu  the  preparation  of  the  food.  These  will  be 
referred  to  in  the  next  section.  The  epithelium  of  the 
intestinal  canal  is  columnar,  except  in  the  oesophagus, 
where  it  is  laminated.  Beneath  the  glandular  layer  of 
the  stomach  is  a  stratum  of  fibrous  connective  tissue  and 
muscle  fibres  in  two  layers,  an  internal  with  transverse, 
and  an  external  with  longitudinal  fibres.  The  tissue  of 
the  small  intestine  beneath  the  epithelium  is  reticular 
connective,  entangling  tymphoid  cells.  The  structure  of 
the  large  intestine  is  similar  to  that  of  the  stomach.  The 
villi  of  the  small  intestine  begins  at  the  pylorus,  flat  and 
low  at  first,  but  becoming  conical,  and  finally  finger-like 
in  shape.  The  epithelium  of  the  villi  are  columnar,  with 
a  thickened  and  perforated  edge  (Plate  XXII,  Fig.  161). 
Between  the  epithelial  cells  of  the  villi,  peculiar  "  goblet- 
cells"  are  often  found,  which  Frey  supposes  to  be  decay- 
ing cells.  The  reticular  connective  tissue  of  each  villus 
is  traversed  by  a  vascular  network,  a  lymphatic  canal  or 
lacteal,  and  delicate  longitudinal  muscular  fibres.  If  the 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          207 

villus  is  unusually  broad,  there  may  be  more  than  one 
lacteal.  The  lacteals  absorb  the  fluid  known  as  chyle. 
They  are  blind  ducts,  and  nitrate  of  silver  injections  show 
them  to  have  the  same  structure  as  other  lymphatics. 

The  lymphatic  radicles  are  widely  disseminated  through 
all  the  tissues  and  organs  of  the  body.  They  take  up  nu- 
tritive fluids,  either  from  the  alimentary  canal,  or  such  as 
have  transuded  from  the  capillaries  into  the  interstices  of 
the  body,  mingled  with  the  products  of  decomposition, 
and  convey  them  into  the  general  circulation.  Hyrtl's 
method  of  demonstrating  these  radicles  is  by  passing  a 
fine  canula  into  the  tissue  containing  lymphatics  and  forc- 
ing the  injection  by  gentle  pressure.  They  are  either  net- 
works, analogous  to  capillaries,  or  blind  passages  which 
unite  in  reticulations.  The  structure  of  the  vessels  has 
already  been  described,  page  201.  Lymphatics  and  capil- 
laries do  not  communicate  directly.  A  lymph-canal  may 
be  surrounded  by  capillaries,  or  run  alongside  of  a  capil- 
lary, or  a  lymphatic  sheath  may  envelop  a  bloodvessel. 
This  latter  plan  is  seen  in  the  nervous  centres,  and  has 
been  called  by  His  the  perivascular  canal  system. 

The  larger  lymphatic  trunks  are  interrupted  by  nodular 
and  very  vascular  organs,  the  lymphatic  glands.  These 
consist  of  the  reticular  connective  tissue  already  described, 
surrounded  by  an  envelope  of  ordinary  fibrous  tissue.  One 
or  more  afferent  lymphatic  vessels  penetrate  the  capsule, 
or  envelope,  and  similar  efferent  vessels  make  their  exit 
from  the  other  side.  Frey  describes  these  glands  as  con- 
sisting of  a  cortical  portion,  follicles,  and  a  medullary 
portion  composed  of  the  tubes  and  reticular  prolongations 
of  the  follicles  (Plate  XXII,  Fig.  162).  There  is  a  corn- 
plicate  system  of  communication  between  the  follicles. 
The  afferent  vessel  opens  into  the  investing  spaces  of  the 
follicle.  These  lead  into  the  lymph-passages  of  the  med- 
ullary portion,  from  the  confluence  of  which  the  radicles 
of  the  efferent  vessels  are  formed.  The  lingual  follicular 


208  THE    MICROSCOPIST. 

glands  and  tonsils,  the  solitary  and  agminated  glands  of 
the  intestine  (Peyer's  patches),  the  thymus,  and  the  spleen 
have  a  similar  structure,  and  are  called  lymphoid  organs. 

In  the  thoracic  duct  the  epithelium  is  inclosed  in  several 
layers  of  fibrous  membrane.  The  latter  contains  trans- 
verse muscular  fibres.  The  heart,  although  an  involuntary 
muscular  organ,  has  striated  muscular  fibres.  These  fibres 
are  not,  like  other  striped  muscles,  collected  into  bundles, 
but  are  reticular.  The  heart,  like  other  organs,  is  supplied 
with  lymphatics  and  bloodvessels.  The  cardiac  plexus  of 
nerves  consists  of  branches  from  the  vagus  and  sympa- 
thetic. Numerous  microscopic  nervous  ganglia  also  occur, 
especially  near  the  transverse  groove  and  septum  of  the 
ventricles.  It  is  thought  that  these  are  the  chief  centres 
of  energy,  so  that  the  heart  pulsates  after  its  removal  from 
the  body.  It  has  also  been  shown  recently  that  the  sym 
pathetic  and  vagus  filaments  are  in  antagonism,  so  that 
stimulation  of  the  vagus  interrupts  the  motor  influence  of 
the  sympathetic,  and  may  bring  the  heart  to  a  standstill 
in  a  condition  of  diastole. 

The  structure  of  bloodvessels  has  been  described  under 
the  head  of  vascular  tissue.  £s"o  special  boundary  exists 
between  capillaries  and  the  arteries  and  veins.  The  ar- 
rangement of  the  capillaries,  however,  is  various,  and 
often  so  characteristic  that  a  practiced  eye  can  generally 
recognize  an  organ  or  tissue  from  its  injected  capillaries. 
(Plate  XXII,  Figs.  163  to  168.)  For  methods  of  inject- 
ing, see  page  64.  Capillaries  form  either  longitudinal  or 
rounded  meshes.  The  muscular  net\vork,  etc. ,  is  extended, 
while  fat-cells,  the  alveoli  of  the  lungs,  lobules  of  liver, 
capillary  loops  of  papillae  in  skin  and  mucous  membranes, 
outlets  of  follicles,  etc.,  present  a  more  or  less  circular  in- 
terlacement. The  capillary  tube  lies  external  to  the  ele- 
mentary structure,  and  never  penetrates  its  interior. 

2.  Secretive  Organs. — True  secretions  serve  important 
offices  in  the  organism :  as  the  materials  of  reproduction ; 


PLATE  XXII. 


FIG.  161. 


Intestinal  Villas. 


FIG. 163. 


Capillary  net-work  around  Fat-cells. 
FIG.  165. 


Distribution  of  Capillaries 
in  Mucous  Membrane. 


Vllli  of  Small  Intestine  of  Monkey. 


Lymphatic  Gland. 
FIG. 164. 


Capillary  net-work  of  Muscle. 
FIG. 166. 


Distribution  of  Capillary  bloodvessels 
in  Skin  of  Finger. 


Arrangement  of  the  Capillaries  of  the  air-cells  of 
the  Human  Lung. 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          209 

milk  from  the  mammary  gland;  saliva,  gastric  juice  and 
pancreatic  fluid  for  digestion.;  mucus,  sebaceous  matter, 
tears,  etc.  Excretions  result  from  waste  or  decomposi- 
tion, and  are  incapable  of  further  use;  as  carbonic  acid, 
separated  by  the  lungs ;  urea,  uric  acid,  etc.,  by  the  kid- 
neys ;  saline  matters,  from  kidneys  and  skin  ;  lactic  acid, 
portions  of  bile,  and  some  of  the  components  of  faeces. 

The  sweat  glands  in  the  skin  are  simply  convoluted  tubes 
lined  with  glandular  epithelium  and  surrounded  by  a 
basket-like  plexus  of  capillaries.  The  sebaceous  glands  are 
racemose,  and  often  open  into  the  hair-follicles. 

The  salivary  glands  are  complex  mucous  glands,  and 
the  saliva  secreted  by  them  is  a  complex  mixture.  The 
terminal  nerves  of  the  submaxillary  gland  have  been  traced 
to  the  nuclei  of  the  gland-cells. 

The  lingual  glands,  and  parotid,  partake  of  the  nature 
of  lymphoid  organs.  The  glands  of  the  oesophagus  are 
racemose.  In  the  stomach  there  are  two  kinds,  the  peptic, 
and  gastric  mucous  glands.  The  peptic  glands  are  blind 
tubes  closely  crowded  together  over  the  mucous  mem- 
brane, lined  with  columnar  epithelium  near  their  open- 
ings, and  gland-cells  below.  The  mucous  glands  are  nu- 
merous near  the  pylorus,  and  are  usually  branching  tubes. 
The  capillaries  are  arranged  in  long  meshes  about  the 
peptic  glands,  and  form  a  delicate  network  in  the  submu- 
cous  tissue.  Numerous  lymphatic  radicles  communicate 
with  lymph-vessels  below  the  peptic  glands. 

The  small  intestine  contains  the  racemose  glands  of 
Brunner  and  the  tubular  follicles  of  Lieberkuhn,  together 
with  the  lymphoid  follicles  known  as  the  solitary  and 
agminated  glands  of  Peyer.  The  glands  of  Brunner  are 
confined  to  the  duodenum,  and  their  excretory  duct  and 
gland  vesicle  are  lined  by  columnar  epithelium.  Lieber- 
kuhn's  follicles  are  found  in  great  numbers  all  over  the 
small  intestine.  Peyer's  patches  are  most  numerous  in 
the  ileum.  They  are  accumulations  of  solitary  glands, 

14 


210  THE    MICROSCOPIST. 

and  their  structure  is  similar  to  the  follicles  of  a  lymphatic 
gland.  The  gland  vesicles  of  the  pancreas  are  roundish, 
and  like  other  salivary  glands  it  is  invested  with  a  vascu- 
lar network  with  rounded  meshes. 

The  liver  is  the  largest  gland  connected  with  nutrition. 
Few  animals  are  without  a  liver  or  its  structural  equiva- 
lent. In  polyps  the  liver  is  represented  by  colored  cells 
in  the  walls  of  the  stomach  cavity.  In  annelids  the  biliary 
cells  cluster  round  csecal  prolongations  of  the  digestive 
cavity.  In  Crustacea  the  liver  consists  of  follicles,  and  in 
insects  of  tubes,  opening  into  the  intestine.  In  all  cases 
the  essential  elements  are  glandular  cells  containing  col- 
oring matter,  oil,  etc.  In  vertebrates  some  parts  of  the 
structure  have  not  been  decided  upon  without  controversy. 

In  man  the  liver  is  a  large,  solid,  reddish-brown  gland, 
about  twelve  inches  across,  and  six  or  seven  inches  from 
anterior  to  posterior  edge,  and  weighing  three  or  four 
pounds,  situated  in  the  right  hypochondrium,  and  reach- 
ing over  to  the  left.  It  is  divisible  into  right  and  left 
lobes  by  the  broad  peritoneal  ligament  above,  and  the 
longitudinal  fissure  beneath.  From  the  latter  a  groove 
passes  transversely  on  the  right  side,  lodging  the  biliary 
ducts,  sinus  of  the  portal  vein,  hepatic  artery,  lymphatics, 
and  nerves,  which  are  enveloped  in  areolar  tissue,  called 
the  capsule  of  Glisson.  From  this  groove  ramifications 
of  the  portal  canal  extend  through  the  liver,  so  numerous 
that  no  part  of  the  hepatic  substance  is  further  than  one- 
thirtieth  of  an  inch  from  them.  These  ramifications 
carry  the  branches  of  the  portal  vein  from  which  the 
capillary  plexus  surrounding  the  lobules  begin,  together 
with  the  bile-ducts,  hepatic  artery,  etc. 

The  hepatic  lobules  are  readily  distinguished  by  the 
naked  eye  in  many  mammals,  as  the  hog,  but  less  easily 
in  human  liver.  They  consist  essentially  of  innumerable 
gland-cells,  and  a  complex  network  of  vessels  which  tend 
towards  the  centre  of  the  lobule,  where  their  confluence 


PLATE  XXIII. 


FIG.  169. 


Lobule  of  Liver. 


FIG. 171. 


Uriniferous  Tubes  of  Kidney. 


FIG.  173. 


Blood-vessels  of  Kidney. 


Tactile  Papillae. 


FIG.  174. 


FIG.  172. 


Alveoli  of  Lung. 


Taste-buds. 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.         211 

forms  the  radicle  of  the  hepatic  vein  ;  while  externally 
the  lobules  are  bounded  by  branches  of  the  portal  vein 
and  biliary  canals  (Plate  XXIII,  Fig.  169).  The  hepatic 
artery  nourishes  the  proper  connective  tissue  of  the  organ, 
and  its  venous  radicles  return  the  blood  to  the  portal 
vein.  The  liver  or  bile-cells  lie  between  the  meshes  of 
the  capillaries,  and  are  irregularly  polyhedral  from  pres- 
sure, soft,  granular,  and  nucleated.  Brown  pigment-gran- 
ules and  fatty  globules  are  also  found  in  the  cells,  and  in 
disease  in  increased  quantity.  These  bile-cells  are  inclosed 
in  a  delicate  reticulated  membrane,  and  Hering  considers 
them  to  have  a  plexus  of  fine  bile-ducts  around  them. 

The  kidneys  are  two  large  bean-shaped  organs,  each 
covered  with  a  thin  but  strong  fibrous  envelope  or  tunic, 
which  is  continuous  round  the  organ  to  the  hilus,  where 
the  ureter  leaves  the  gland  and  the  bloodvessels  enter. 
Even  with  the  naked  eye  we  may  distinguish  in  a  section 
of  kidney  the  external  granular  cortex  and  the  fibrous  or 
striped  medullary  portion.  The  lines  of  the  latter  con- 
verge towards  the  hilus,  and  generally  in  a  single  conoid 
mass ;  but  in  man  and  some  other  animals  this  is  divided 
into  sections,  called  the  pyramids,  and  between  them  the 
cortical  substance  is  prolonged  in  the  form  of  septse,  while 
both  portions  contain  interstitial  connective  tissue.  Both 
the  cortical  and  medullary  portions  contain  long  branch- 
ing glandular  tubes,  called  the  uriniferous  tubes.  In  the 
medullary  part  these  tubes  are  straight  and  divide  at 
acute  angles,  while  in  the  cortex  they  are  greatly  convo- 
luted and  terminate  in  blind  dilatations,  the  capsules  of 
Bowman.  Staining  with  nitrate  of  silver  shows  the  cap- 
sules to  be  lined  with  delicate  pavement-epithelium.  The 
convoluted  tubes  proceeding  from  the  capsules,  containing 
thick  granular  gland-cells,  after  numerous  windings  in  the 
cortex,  arrive  at  the  medullary  portion,  where  each  pur- 
sues a  straight  course,  and  is  lined  with  flat  pavement- 
epithelium  similar  to  the  endothelium  of  vascular  tissue. 


212  THE    MICROSCOPIST. 

Kear  the  base  of  the  pyramids  these  tubes  curve  upwards, 
forming  the  looped  tubes  of  Ilenle.  The  recurrent  tubes 
enlarge,  and  exhibit  the  ordinary  cubical  gland-cell. 
These  tubes  also  become  more  tortuous,  and  empty  into 
others  of  larger  calibre,  called  collecting  tubes.  These 
are  lined  with  low  columnar  epithelium,  and  uniting  with 
similar  tubes  at  acute  angles,  give  exit  to  the  urine  at  the 
apex  of  the  papillae  in  the  pyramids  (Plate  XXIII,  Fig. 
170). 

The  bloodvessels  of  the  kidney  are  as  complex  as  the 
glandular  tissue.  Both  vein  and  artery  enter  at  the  hilus 
of  the  kidney,  and  after  giving  twigs  to  the  external 
tunic,  proceed  between  the  pyramids  as  far  as  their  bases. 
Here  they  give  off  curving  branches,  forming  imperfect 
arches  among  the  arteries,  and  complete  anastomosing 
rings  on  the  veins.  From  the  arterial  arches  spring  the 
branches  which  bear  the  glomeruli  of  the  cortical  sub- 
stance or  Malpighian  tufts  (Plate  XXIII,  a,  Fig.  171). 
The  afferent  vessel  of  the  glomerulus  subdivides,  and  after 
coiling  and  twisting  within  the  capsule  of  Bowman,  gives 
origin  to  the  efferent  vessel,  by  the  union  of  the  small 
branches  thus  formed.  This  efferent  vessel  breaks  up  into 
a  network  of  fine  capillaries,  with  elongated  meshes  sur- 
rounding the  straight  uriniferous  canals.  From  the  periph- 
ery of  this  network  somewhat  wider  tubes  are  given  off, 
which  surround  with  rounded  meshes  the  convoluted  tubes 
of  the  cortex. 

The  long  bundles  of  vessels  between  the  uriniferous  tubes 
of  the  medulla,  communicating  in  loops  or  forming  a  deli- 
cate network  round  the  mouths  of  the  canals  at  the  apex 
of  the  papillae  are  called  the  vasa  recta. 

The  ureters,  like  the  pelvis  of  the  kidney,  consist  of  an 
external  fibrous  tunic,  a  middle  layer  of  smooth  muscular 
fibres,  and  an  internal  mucous  membrane  with  a  layer  of 
epithelium.  The  bladder  is  covered  externally  with  a 
serous  membrane,  the  peritoneum.  The  female  urethra  is 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          213 

lined  by  mucous  membrane,  with  vascular  walls  full  of 
folds,  and  containing,  near  the  bladder,  a  number  of  mu- 
cous glands. 

3.  Respiratory   Organs. — The  lungs  receive  air  by  the 
trachea  and  venous  blood  from  the  rio-ht  side  of  the  heart 

O 

to  transmit  to  the  left  side.  They  may  be  compared,  as 
to  form  and  development,  to  racemose  glands.  The  ex- 
cretory ducts  are  represented  by  the  bronchial  ramifica- 
tions, and  the  acini  by  the  air-vesicles. 

The  ciliated  mucous  membrane  of  the  bronchial  twigs 
gradually  loses  its  laminated  structure  until  only  a  single 
layer  remains.  Their  muscular  layer  also  ceases  before 
arriving  at  the  air-cells.  At  the  end  of  the  last  bronchial 
tubules  we  find  thin-walled  canals  called  alveolar  passages. 
These  are  again  subdivided  and  end  in  peculiar  dilatations 
called  primary  pulmonary  lobules,  or  infundibula  (Plate 
XXIII,  Fig.  172).  The  air-cells,  vesicles,  or  alveoli,  are 
saccular  dilatations  in  the  walls  of  the  primary  lobules, 
opening  directly  into  a  common  cavity.  Their  walls  con- 
sist of  delicate  membrane  of  connective  tissue,  often  con- 
taining black  pigment,  probably  from  inhalation  of  car- 
bonaceous matter,  or  a  deposit  of  melanin. 

The  pulmonary  artery  subdivides,  and  follows  the  rami- 
fications of  the  bronchi  to  the  pulmonary  vesicles.  Here 
a  multitude  of  capillary  tubes  form  a  network  over  the 
alveoli,  only  separated  from  the  air  by  the  most  delicate 
membrane  (Plate  XXII,  Fig.  168).  In  the  frog  we  find 
the  whole  respiratory  portion  lined  with  a  continuous 
layer  of  flattened  epithelia.  A  similar  lining  is  found  in 
the  mammalian  foetus,  but  in  the  adult  the  number  and 
character  of  the  epithelial  scales  is  greatly  changed.  Large 
non-nucleated  plates  are  seen  with  occasional  traces  of  the 
original  bioplasm.  In  inflammatory  affections,  however, 
these  may  multiply,  giving  rise  to  catarrhal  desquamation. 

4.  G-enerative  Organs. — The  histology  of  the  organs  of 
reproduction  is  quite  elaborate,  and  the  plan  of  this  work 


214  THE    MICROSCOPIST. 

only  permits  us  to  glance  at  the  essential  structures, 
which  are  the  seminiferous  tubules  for  the  secretion  of 
spermatozoa,  in  the  male,  and  the  ovary  for  the  production 
of  the  germ,  or  ovum,  in  the  female. 

The  tubidi  seminiferi  are  a  multitude  of  fine  and  tortuous 
tubules  contained  in  the  testis,  with  its  accessory  epididy- 
mis.  They  lie  in  the  interstices  of  sustentacular  connec- 
tive tissue,  and  consist  of  membranous  tubes  filled  with 
cells,  which  are  said  to  possess  amoeboid  motion.  During 
the  virile  period  these  glandular  tubes  generate  the  sper- 
matozoa, or  microscopic  seminal  filaments.  The  shape  of 
these  spermatozoa  is  filiform  in  all  animals,  but  vary  in 
different  species.  In  man  they  consist  of  an  anterior  oval 
portion,  or  head,  and  a  posterior  flexible  filament,  or  tail. 
Different  observers  have  taken  different  views  as  to  the 
origin  of  these  structures.  Some  suppose  them  the  product 
of  special  cells,  others  trace  them  to  the  nuclei  of  the 
glandular  epithelium,  while  others  regard  them  as  ciliated 
elements  formed  by  the  metamorphosis  of  entire  cells. 
Their  motions  baffle  all  attempts  at  explanation,  although 
quite  similar  to  those  of  ciliated  epithelium.  The  sperma- 
tozoa penetrate  by  their  movements  into  the  interior  of 
the  ovum,  in  order  to  impregnate  it,  and  in  the  mammalia 
in  considerable  numbers. 

The  ovary  may  be  divided  into  two  portions:  a  medul- 
lary substance,  which  is  a  non-glandular  and  very  vascular 
connective  tissue,  and  a  glandular  parenchyma  enveloping 
the  latter.  The  surface  of  the  ovary  uncovered  by  peri- 
toneum is  coated  with  a  layer  of  low  columnar  cells,  called 
the  germinal  epithelium.  Immediately  under  this  is  a 
stratum  called  the  zone  of  the  primordial  follicles,  or  cor- 
tical zone.  Here  the  young  ova  lie  crowded  in  layers. 
They  consist  of  granular  bioplasm,  containing  fatty  mol- 
ecules and  a  spherical  nucleus.  They  are  probably  de- 
veloped by  a  folding  in  of  the  germinal  epithelium.  To- 
ward the  internal  portion  of  the  ovary  the  follicles  become 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          215 

more  highly  developed,  and  the  ovum  contained  in  them  is 
also  increased  in  size  and  enveloped  in  a  distinct  mem- 
brane. There  are  from  twelve  to  twenty  mature  follicles 
in  the  ovarium,  named,  from  their  discoverer,  Graafian 
follicles.  Each  has  an  epithelial  lining,  in  which  the  ovum 
is  imbedded.  The  capsule  of  the  ovum  is  known  as  the 
zona  pellucida,  or  chorion,  and  the  albuminous  cell-body  is 
the  vitellus.  The  nucleus  is  situated  exeentrically,  and  is 
called  the  vesicula  germinativa,  or  germinal  vesicle  of  Pur- 
kinje.  Within  it  is  a  round  and  highly  refractive  nucle- 
olus,  the  macula  germinativa,  or  germinal  spot  of  Wagner. 
A  Graafian  vesicle  bursts  and  an  ovum  is  liberated  at 
every  menstrual  period.  During  the  progress  of  the  latter 
down  the  Fallopian  tube  to  the  uterus,  impregnation  may 
take  place  by  the  penetration  of  spermatozoa  into  its  yelk. 
Then  the  inherent  vital  energies  of  the  cell  are  aroused, 
and  the  process  of  segmentation  begins.  Unimpregnated 
ova  are  destroyed  by  solution.  The  ruptured  and  emptied 
Graafian  vesicle  becomes  filled  up  with  cicatricial  connec- 
tive tissue,  which  constitutes  what  is  called  the  corpus 
lute,um,  after  which  it  gradually  disappears. 

II.  ORGANS  OF  ANIMAL  LIFE. 

1 .  Locomotive. — The  microscopic  structure  of  bone  and 
muscle  has  been  described  in  connection  with  elementary 
tissues.     Tendons  and  fascias  belong  to  the  connective 
tissues. 

2.  Sensory. — The  nervous  apparatus  of  the  body,  whose 
histological  elements  were  treated  of  on  a  previous  page, 
has  been  classified  physiologically  into: 

1.  The  sympathetic  system,  consisting  of  a  chain  of  gan- 
glia on  each  side  of  the  vertebral  column,  with  commu- 
nicating cords  or  extensions  of  ganglia,  visceral  nerves, 
arterial  nerves,  and  nerves  of  communication  with  the 
cerebral  and  spinal  nerves.  The  chief  structural  differ- 


21t)  THE    MICROSCOPIST. 

ence  between  this  and  the  cerebro-spinal  system  is  that  in 
the  latter  the  nerve-cells  form  large  masses,  and  the  union 
of  its  parts  is  effected  by  means  of  central  fibres,  while  in 
the  sympathetic  the  cells  are  more  widely  separated,  and 
union  between  them  and  with  the  cerebro-spinal  axis  is 
by  means  of  peripheral  fibres.  The  sympathetic  is  con- 
sidered a  motor  and  sensitive  nerve  to  internal  viscera, 
and  to  govern  the  actions  of  bloodvessels  and  glands. 

2.   The  cerebro-spinal  system,  divided  into : 

(1.)  A  system  of  ganglia  subservient  to  reflex  actions, 
the  most  important  of  which  is  the  spinal  cord,  where  the 
gray  or  vesicular  nervous  matter  forms  a  continuous  tract 
internally. 

(2.)  A  gangliouic  centre  for  respiration,  mastication, 
deglutition,  etc.,  with  a  series  of  ganglia  in  connection 
with  the  organs  of  special  sense:  the  medulla  oblorigata, 
with  its  neighboring  structures;  the  mesocephalon,  cor- 
pora striata,  and  optic  thalami. 

(3.)  The  cerebellum,  a  sort  of  offshoot  from  the  upper 
extremity  of  the  medulla,  for  adjusting  and  combining 
voluntary  motions. 

(4.)  The  cerebrum,  cerebral  hemispheres,  or  ganglia, 
which  are  regarded  as  the  principal  organs  of  voluntary 
movements.  In  the  lower  vertebrates  the  hemispheres 
are  comparatively  small,  so  as  not  to  overlap  the  other 
divisions  of  the  brain ;  but  in  the  higher  Mammalia  they 
extend  over  the  olfactory  lobes  and  backward  over  the 
optic  lobes  and  cerebellum,  so  as  to  cover  these  parts, 
while  they  also  extend  downward  toward  the  base  of  the 
brain.  In  the  lower  vertebrates,  also,  the  surface  of  the 
hemispheres  is  smooth,  while  in  the  higher  it  is  compli- 
cated by  ridges  and  furrows. 

(5.)  The  cerebral  and  spinal  nerves.  The  spinal  nerves 
arise  in  pairs,  generally  corresponding  with  the  vertebrae. 
Each  has  two  roots,  one  from  the  dorsal,  and  one  from 
the  ventral  region  of  its  half  of  the  cord.  The  former 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          217 

root  has  a  ganglionic  enlargement,  and  contains  only  sen- 
sory fibres ;  the  latter  has  no  ganglion,  and  contains  only 
motor  fibres. 

The  cerebral  nerves  are  those  given  off  from  the  base 
of  the  brain.  Some  of  these  minister  to  special  sensation, 
as  the  olfactory,  optic,  auditory,  part  of  the  glosso-pha- 
ryngeal,  and  the  lingual  branch  of  the  trifacial  nerves. 
Some  are  nerves  of  motion,  as  the  motor  oculi,  patheti- 
cus,  part  of  the  third  branch  of  the  fifth  pair,  the  abdu- 
cens,  the  facial  and  the  hypoglossal  nerves.  Others  are 
nerves  of  common  sensation,  as  the  fifth,  and  part  of  the 
glosso-pharyngeal  nerves.  Others,  again,  are  mixed,  as 
the  pneumogastric  and  spinal  accessory  nerves. 

The  minute  structure  of  the  central  organs  of  the  ner- 
vous system  is  excessively  complicate  and  full  of  details. 
Hardening  with  chromic  acid  and  bichromate  of  potash 
is  generally  advisable  before  examination.  This  should 
be  done  with  small  pieces  in  a  large  quantity  of  the  fluid. 
One-eighth  to  one-half  grain  of  bichromate,  or  0.033  to 
0.1  grain  of  chromic  acid,  to  the  ounce  of  water  should 
be  used,  the  strength  gradually  increased  from  day  to 
day.  After  such  maceration  for  several  days,  a  drop  of  a 
28  per  cent,  solution  of  caustic  potash  may  be  added  to 
one  ounce  of  water,  and  the  specimen  soaked  in  it  for  an 
hour,  to  macerate  the  connective  tissue.  After  again  soak- 
ing in  graduated  solutions  of  the  bichromate,  up  to  two 
grains  to  the  ounce,  the  tissue  may  be  carefully  picked 
apart  under  the  dissecting  microscope.  In  such  manner 
Deiters  discovered  the  two  kinds  of  processes  in  the  multi- 
polar  ganglion-cells.  Gerlach  placed  thin  sections  for  two 
or  three  days  in  0.01  to  0.02  per  cent,  solutions  of  bichro- 
mate of  ammonia,  and  picked  them  apart  after  staining 
with  carmine. 

Lockhart  Clarke  placed  parts  of  the  spinal  cord  in  equal 
parts  of  alcohol  and  water  for  a  day,  then  for  several  days 
in  pure  alcohol,  till  thin  sections  could  be  made.  These 


218  THE    MICROSCOPIST. 

were  immersed  for  an  hour  or  two  in  a  mixture  of  one  part 
acetic  acid  and  three  parts  alcohol,  to  render  the  gray 
matter  transparent  and  the  fibrous  elements  prominent. 

Sections  may  be  stained  with  carmine  and  mounted  in 
glycerin  or  balsam  (see  Chapter  Y). 

(6.)  Organs  of  special  sense : 

a.  Organs  of  Touch. — The  tactile  papillae  of  the  skin 
and  Pacinian  corpuscles  may  be  studied  in  thin  sections 
of  fresh  or  dried  skin.     Treatment  with  dilute   acetic 
acid,  or  acetic  acid  and  alcohol,  and  staining  with  car- 
mine, or  chloride  of  gold,  is  recommended.     The  papillae 
are  made  up  of  connective  tissue,  into  which  nervous  fila- 
ments enter,  and  end  in  peculiar  tactile  corpuscles  (Plate 
XXIII,  Fig.  173).     The  structure  of  the  skin  itself,  with 
its  various  layers  and  sudoriparous  glands,  may  be  seen 
in  such  sections. 

b.  Organs  of  Taste. — The  terminations  of  the  gustatory 
nerves  of  the  tongue  are  yet  imperfectly  known.     In  the 
circumvallate  papillae,  on  the  side  walls,  certain  structures 
are  found,  called  gustatory  buds  or  taste-cups  (Plate  XXIII, 
Fig.  174).     They  consist  of  flattened  lanceolate-cells,  ar- 
ranged like  the  leaves  of  a  flower-bud,  and  containing 
within  them  fusiform  gustatory  cells,  which  end  in  rods, 
and  filaments  projecting  from  the  rods  above  the  buds 
are  seen  in  some  animals.     Underneath  is  a  plexus  of  pale 
and  medullated  nerve-fibres.     The  mode  of  nervous  ter- 
mination in  the  fungiform  papillae  is  not  known.     For  pri- 
mary examination,  sections  of  the  dried  tongue  may  be 
softened  in  dilute  acetic  acid  and  glycerin,  or  hardened  in 
osmic  acid.     For  the  finer  structure,  maceration  in  iodine 
serum,  and  immersion  in  one-half  per  cent,  chromic  acid, 
with   an  equal   quantity   of  glycerin,  is   recommended. 
Careful  picking  under  the  simple  microscope  is  necessary. 
Sections  may  also  be  stained  with  chloride  of  gold. 

c.  Organs  of  /Smell. — In  the  olfactory  regions,  which  are 
patches  of  yellowish  or  brownish  color  on  the  upper  and 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.         219 

deeper  part  of  the  nasal  cavity,  we  find  nucleated  cylin- 
drical cells  taking  the  place  of  ordinary  ciliated  epithe- 
lium, and  sending  processes  downward,  which  communi- 
cate with  each  other,  forming  a  delicate  network  (Plate 
XXI Y,  Fig.  175).  Between  these  cells  we  find  the  olfac- 
tory cells,  spindle-shaped  nucleated  bodies,  extending  up- 
ward into  a  fine  rod  and  downward  into  a  varicose  fila- 
ment. In  birds  and  amphibia  these  rods  are  terminated 
by  delicate  hairs,  some  of  which  have  ciliary  motion. 
Beneath  these  structures  are  peculiar  glands,  consisting 
of  pigmented  gland-cells.  They  are  called  Bowman's 
glands.  The  branches  of  the  olfactory  nerve  proceed  be- 
tween these  glands  and  branch  out  into  fine  varicose  fila- 
ments, which  are  supposed  to  communicate  with  the 
olfactory  cells.  Hardening  in  chromic  acid,  or  Muller's 
fluid,  or  a  concentrated  solution  of  oxalic  acid,  or  one- 
half  to  one  per  cent,  solution  of  sulphuric  acid,  is  neces- 
sary for  the  preservation  of  these  delicate  structures. 

d.  Organs  of  Sight. — As  in  the  sense  of  touch  certain 
tactile  papillae  detect  deviations  from  the  general  surface  ; 
and  in  that  of  taste  special  rod-like  end  organs  and  their 
covering  bulbs  distinguish  the  solutions  of  different  sapid 
substances ;  and  as  in  smelling,  not  the  whole  organ  but 
olfactory  regions-,  with  peculiar  cells  and  nervous  rods, 
discriminate  mechanical  or  chemical  odors,  so  in  vision  a 
special  apparatus  is  provided  to  perceive  the  wonderful 
variety  of  colors  and  forms.  The  minute  structure  of 
organs  becomes  more  complex  in  proportion  as  they  serve 
the  higher  functions  of  mind. 

The  various  tunics  and  accessory  structures  of  the  eye 
are  described  in  most  text-books  ;  we  here  limit  ourselves 
to  a  brief  reference  to  those  refracting  and  receptive  struc- 
tures whose  office  it  is  to  translate  the  phenomena  of  light 
into  those  of  nervous  conduction. 

Externally,  we  have  in  front  of  the  eye  the  transparent 
cornea.  This  is  made  of  connective  tissue  with  cells,  bun- 


220  THE    MICROSCOPIST. 

dies  of  fibres,  and  cavities  containing  cells.  Its  tissues  are 
in  layers,  as  follows :  1.  External  epithelium,  flat  and 
laminated.  2.  Anterior  basement-membrane  or  lamina. 
3.  True  corneal  tissue.  4.  Membrane  of  Descemet  or 
Demours.  5.  Endothelium  with  flat  cells  (Plate  XXIY, 
Fig.  176).  The  cells  of  corneal  tissue  are  of  two  forms. 
The  first  are  wandering  or  amoeboid  cells,  and  may  be 
seen  in  a  freshly  extirpated  frog's  cornea  placed  underside 
up,  with  aqueous  humor  in  a  moist  chamber,  on  the  stage 
of  the  microscope.  If  a  small  incision  be  made  at  the 
margin  of  the  cornea  of  a  living  frog  a  few  hours  before 
its  extraction,  and  vermilion,  carmine,  or  anilin  blue  is 
rubbed  in,  the  cells  which  have  absorbed  the  coloring 
matter  will  be  found  at  some  distance  afterwards,  having 
wandered  like  leucocytes  or  pus-cells  elsewhere.  Their 
origin  may  be  from  blood  or  true  corneal  corpuscles,  or 
both.  The  second  form,  or  corneal  corpuscles,  are  im- 
movable, flat,  with  branching  or  stellate  processes.  They 
may  be  demonstrated  by  staining  with  chloride  of  gold 
or  nitrate  of  silver.  The  bundles  of  fibrillar  substance  in 
the  cornea  pass  in  various  directions,  and  the  natural 
cavities  in  it  contain  the  corneal  cells.  As  stated,  the 
nerves  of  the  cornea  have  been  traced  to  the  external 
epithelium,  which  sometimes  contains-  serrated  (riff'  or 
stachell)  cells. 

The  aqueous  humor  is  structureless,  but  the  vitreous 
humor  is  supposed  to  have  delicate  membranous  septa. 
The  crystalline  lens  consists  of  a  capsule  inclosing  a  tissue 
of  fine  transparent  fibres  or  tubules,  which  are  of  epithe- 
lial origin.  These  fibres  are  flat,  and  often  have  serrated 
borders,  especially  in  fishes. 

The  retina,  or  nervous  portion  of  the  eye,  is  the  most 
important,  as  its  delicacy  and  liability  to  decomposition 
render  it  the  most  difficult  object  of  microscopic  exami- 
nation. 

We  must  dismiss  the  popular  notion  of  minute  images 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          221 

produced  on  the  retina  by  the  lens  to  be  viewed  by  the 
mind.  The  lens  does,  indeed,  form  an  image  on  the  mem- 
brane, so  it  would  on  glass  or  paper,  but  the  real  action 
of  the  vibrations  of  light  upon  the  nervous  conductors  is 
not  thus  to  be  explained. 

The  complex  structure  of  the  retina  is  only  recently 
known,  and  it  may  be  that  many  laws  of  light  yet  un- 
known are  to  be  exhibited  by  its  means,  as  well  as  much 
that  relates  to  the  connection  of  the  perceiving  thinking 
mind  and  the  external  world. 

Muller's  fluid,  concentrated  solution  of  oxalic  acid,  0.6 
per  cent,  solution  of  sulphuric  acid,  and  0.1  to  2  per  cent, 
solutions  of  osmic  acid,  may  be  used  for  hardening,  but 
very  delicate  dissection  is  required  for  demonstration. 
Rutherford  recommends  chromic  acid  and  spirit  solution, 
1  gramme  of  chromic  acid  in  20  c.c.  of  water,  and  180  c.c. 
of  methylated  spirit  added  slowly. 

The  retina  consists  of  the  following  layers  :  1.  The 
columnar  layer,  or  layer  of  rods  and  cones.  2.  Membrana 
limit.ans  externa.  3.  External  granular  layer.  4.  Inter- 
granular  layer.  5.  Internal  granular  layer.  6.  Molecular 
layer.  7.  Ganglionic  cell  layer.  8.  Expansion  of  optic 
nerve.  9.  Membrana  limitans  interna.  To  these  may  be 
added  :  10.  The  pigment  layer,  often  described  as  the 
pigmented  epithelium  of  the  choroid,  into  which  the  rods 
and  cones  project.  These  layers  are  composed  of  two 
different  elements,  mutually  blended,  a  connective-tissue 
framework  of  varying  structure  in  the  different  layers, 
and  a  complex  nervous  tissue  of  fibres,  ganglia,  rods,  and 
cones.  Plate  XXIV,  Fig.  177,  is  a  diagram  of  these 
separate  structures,  after  M.  Shultze,  in  Strieker's  Man- 
ual of  Histology. 

The  structure  of  the  rods  and  cones  is  complex,  and 
varies  in  different  animals.  The  rods  readily  decompose, 
becoming  bent  and  separated  into  disks,  but  examination 
of  well-preserved  specimens  shows  them  to  have  a  fibril- 


222  THE    MICROSCOPIST. 

lated  outer  covering.  In  addition,  certain  globular  or 
lenticular  refractive  bodies,  of  different  shape  and  color 
in  different  animals,  are  found  in  these  structures  (Plate 
XXIY,  Fig.  178),  which  doubtless  are  designed  to  give 
the  rays  of  light  such  a  direction  for  final  elaboration  in 
the  outer  segment  as  they  could  not  receive  from  the 
coarser  refractive  apparatus  in  the  front  of  the  eye. 

e.  Organs  of  Hearing. — These  are  most  intimately  con- 
nected with  mental  functions,  because  of  language,  which 
is  the  highest  sensual  expression  of  mind.  Hence  the 
structure  of  these  organs  is  most  delicate  and  complex. 

The  labyrinth  is  the  essential  part  of  the  organ,  con- 
sisting in  man  of  the  vestibule,  the  semicircular  canals, 
and  the  cochlea.  Sonorous  undulations  are  propagated 
to  the  fluid  in  the  labyrinth  through  the  tympanum  and 
chain  of  otic  bones. 

The  auditory  nerves  are  distributed  to  the  ampullre  and 
sacculi  of  the  vestibule,  and  to  the  spiral  plate  of  the 
cochlea.  At  the  terminal  filaments  in  the  sac  of  the 
vestibule,  crystals,  called  otoliths,  of  shapes  differing  in 
various  animals,  are  inclosed  in  membrane.  Hasse  con- 
siders them  to  be  vibrating  organs,  but  Waldeyer  regards 
their  function  to  be  that  of  dampening  sound. 

As  we  distinguish  in  sounds  the  various  qualities  of 
pitch,  intensity,  quality,  and  direction,  it  is  probable  that 
there  is  a  special  apparatus  for  each,  but  histology  has 
not  yet  established  this  fully.  Kolliker  thinks  the  gan- 
glionic  termination  of  the  cochlear  nerve  renders  it  proba- 
ble that  it  only  receives  sonorous  undulations.  The  ex- 
periments of  Flourens  seem  to  show  that  the  semicircular 
canals  influence  the  impression  of  direction  of  sound. 

In  the  sacs  of  the  vestibule  and  ampullae,  the  nerve- 
fibres  are  confined  to  a  projection  of  the  walls  called  the 
septum  nerveum.  Here  are  found  cylinder-  and  fibre-cells, 
with  rods,  basal-cells,  and  nerves.  But  it  is  in  the  lamina 
spiralis  of  the  cochlea  that  the  most  elaborate  organ, 


PLATE  XXIV.  , 


FIG.  175. 


U  N  I V  E  R  8 1 T  Y 

••'.-VLIFORNJ 

FIG. 176. 


Olfactory  cells. 


Section  of  Cornea. 


FIG. 177. 


FIG. 179. 


vi  nil 
fefe 


Connective-tissue  and  nerve-elements  of  Retina. 
Showing  rods  and  cones. 

FIG.  178. 

"Id 


: 


Refractive  bodies  in  the  rods  and  cones. 


Section  of  Cochlea: — v,  scala  vestibuli ;  T,  scala 
tympani ;  c,  canal  of  Cochlea;  R,  Reissner's  mem- 
brane, attached  at  a  to  the  habenula  sulcata;  6 
connective-tissue  layer;  c,  organ  of  Corti. 


FIG.  180. 


Corti's  organ,  from  above. 


FIG. 181. 


Section  of  Corti's  organ. 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          223 

called  from  its  discoverer  the  organ  of  Corti,  is  found. 
Kolliker  considers  the  free  position  of  the  expanded  por- 
tion of  the  nerve,  and  the  extent  of  surface  over  which 
its  terminal  fibres  are  spread,  to  constitute  it  an  organ  of 
great  delicacy,  enabling  us  to  distinguish  several  sounds 
at  once  and  to  determine  their  pitch.  There  is  a  striking 
analogy  between  the  visual  and  auditory  apparatus  in  the 
ganglionic  structure  of  the  nerve-structure.  Plate  XXIV, 
Fig.  179,  represents  a  vertical  section  through  the  tube 
of  the  cochlea ;  and  Plate  XXIV,  Figs.  180  and  181,  the 
vestibular  aspect  and  a  vertical  section  of  Corti's  organ. 

Waldeyer  recommends  examination  of  the  cochlea  in  a 
fresh  state  and  in  aqueous  humor.  Preparations  in  osmic 
acid  and  chloride  of  gold  are  also  useful.  For  sections  he 
removes  much  of  the  bony  substance  of  large  cochleae  with 
cutting  pliers,  opens  the  membrane  in  several  places,  and 
places  the  specimen  in  0.001  per  cent,  of  chloride  of  palla- 
dium, or  0.2  to  1  per  cent,  osrnic  acid  solution  for  twenty- 
four  hours,  then  for  the  same  time  in  absolute  alcohol. 
It  is  then  treated  with  a  fluid  composed  of  0.001  per  cent, 
chloride  of  palladium  with  one-tenth  part  of  J  to  1  per 
cent,  muriatic  or  chromic  acid,  to  deprive  it  of  earthy 
salts.  It  is  then  washed  in  absolute  alcohol,  and  inclosed 
in  a  piece  of  marrow  or  liver,  and  placed  to  harden  in 
alcohol  again.  The  hollows  of  the  cochlea  may  be  filled 
with  equal  parts  of  gelatin  and  glycerin  before  they  are 
inclosed.  Sections  must  be  cut  with  a  sharp  knife. 

Rutherford  advises  the  softening  of  the  bone  and  hard- 
ening of  other  tissues  by  maceration  in  chromic  acid  and 
spirit  (1  gramme  of  chromic  acid  in  20  c.c.  of  water,  and 
180  c.c.  of  methylated  spirit  slowly  added).  For  sections 
he  commends  Strieker's  mode  of  imbedding  in  gum.  Place 
the  cochlea  in  a  small  cone  of  bibulous  paper,  containing 
a  strong  solution  of  gum  arabic,  for  four  or  five  hours ; 
then  immerse  the  cone  in  methylated  spirit  for  forty-eight 


224  *      THE    MICROSCOPIST. 

hours,  or  until  the  gum  is  hard  enough.  The  sections 
may  be  stained  with  carmine,  logwood,  silver,  or  gold. 

The  following  suggestions  from  Rutherford's  Outlines 
of  Practical  Histology,  will  be  of  service  to  the  student  in 
this  department : 

Most  of  the  tissues  required  may  be  obtained  from  the 
cat  or  guinea-pig.  Feed  the  cat,  and  an  hour  or  so  after 
place  it  in  a  bag ;  drop  chloroform  over  its  nose  until  it  is 
insensible.  Open  the  chest  by  a  linear  incision  through 
the  sternum,  and  allow  the  animal  to  bleed  to  death  from 
a  cut  in  the  right  ventricle. 

Divide  the  trachea  below  the  cricoid  cartilage  and  in- 
ject it  with  J  per  cent,  chromic  acid  fluid  ;  tie  it  to  prevent 
the  escape  of  fluid,  and  place  the  distended  lungs  in  the 
same  fluid,  and  cover  them  with  cotton-wool.  Change 
the  fluid  at  the  end  of  eighteen  hours.  Allow  them  to 
remain  in  this  fluid  for  a  mouth,  then  transfer  to  methy- 
lated spirit  till  needed  for  mounting. 

Open  by  a  linear  incision  the  oesophagus,  stomach,  large 
and  small  intestines,  and  wash  them  with  salt  solution  (f 
per  cent.).  Place  a  portion  of  small  intestine  in  chromic 
and  bichromate  fluid  (1  gramme  chromic  acid  and  2 
grammes  potassium  bichromate  in  1200  c.c.  water)  for  two 
weeks  (change  the  fluid  at  the  end  of  eighteen  hours),  and 
then  in  methylated  spirit  till  required.  Act  similarly 
with  parts  of  oesophagus,  stomach  and  large  intestine,  in 
J  per  cent,  chromic  acid  for  three  or  four  weeks.  A  por- 
tion of  stomach  may  be  placed  in  Muller's  fluid  till  re- 
quired for  preparation  of  non-striped  muscle,  and  of  the 
gastric  follicles. 

The  bladder  may  be  treated  as  the  small  intestine. 

Divide  one  kidney  longitudinally,  and  the  other  trans- 
versely, and  place  in  Muller's  fluid.  Change  the  fluid  in 
eighteen  hours,  and  after  four  weeks  transfer  to  methy- 
lated spirits.  They  will  be  ready  for  use  in  two  weeks 
after. 


THE    MICROSCOPE    IN    ANIMAL    HISTOLOGY.          225 

Cut  one-half  of  the  liver  into  small  pieces  and  prepare 
as  the  kidneys.  The  tongue,  divided  transversely  into  five 
or  six  pieces,  the  spleen,  uterus,  and  thin  muscles  from 
limbs  or  abdomen,  in  J  per  cent,  chromic  acid.  Change  as 
before,  and  in  a  month  to  methylated  spirit. 

Testis  of  dog,  freely  incised,  and  ovaries  of  cat  or  dog,  in 
Muller's  fluid,  and  after  three  weeks  to  methylated  spirits. 

Divide  the  eyes  transversely  behind  the  lens.  Remove 
the  vitreous.  Place  posterior  halves  in  chromic  and  spirit 
solution.  Change  in  eighteen  hours.  Transfer  to  methy- 
lated spirit  in  ten  days.  Place  the  lens  in  Muller's  fluid 
for  five  weeks,  and  then  in  methylated  spirits.  The  cor- 
nea may  remain  in  J  per  cent,  chromic  acid  for  a  month, 
and  then  in  methylated  spirit. 

Cautiously  open  the  cranial  and  spinal  cavities.  Re- 
move brain  and  cord,  and  strip  off  arachnoid.  Partially 
divide  the  cord  into  pieces  a  half  inch  long.  Partially 
divide  the  brain  transversely  into  a  number  of  pieces. 
Place  in  a  cool  place  in  methylated  spirits  for  eighteen 
hours.  Transfer  cord  to  J  per  cent,  chromic  acid  for  six 
or  seven  weeks.  Change  in  eighteen  hours.  Prepare  the 
sciatic  nerve  in  the  same  manner.  Place  the  brain  in 
chromic  and  bichromate  fluid.  Change  in  eighteen  hours, 
and  then  once  a  week,  until  the  brain  is  hard.  If  not 
leathery  in  six  weeks  place  in  J  per  cent,  chromic  acid  for 
two  weeks,  and  then  in  methylated  spirits.  Support  the 
brain  and  cord  on  cotton-wool  in  the  hardening  fluid. 

Remove  muscles,  but  riot  periosteum  from  bones  of 
limbs,  and  both  from  the  lower  jaw.  Divide  the  bones 
transversely  in  two  or  three  places,  and  put  them  in  chro- 
mic and  nitric  fluid  (chromic  acid,  1  gramme  ;  water,  200 
c.c. ;  then  add  2  c.c.  nitric  acid).  Change  the  fluid  often 
until  the  bone  is  soft  enough,  and  transfer  to  methylated 
spirits.  If  not  complete  in  a  month,  double  the  quantity 
of  nitric  acid  in  the  fluid. 

15 


226  THE    MICROSCOPIST. 

Place  a  piece  of  human  scalp,  skin  from  palmar  surface 
of  finger,  and  skin  of  dog  (for  muscles  of  hair-follicles)  in 
chromic  and  spirit  fluid.  In  a  month  transfer  to  methy- 
lated spirit. 

Remove  the  petrous  portion  of  temporal  bone,  open  the 
tympanum,  pull  the  stapes  from  the  oval  fenestra,  and  place 
the  cochlea  in  chromic  and  spirit  fluid.  Change  in  eighteen 
hours,  and  at  the  end  of  seven  days,  if  a  brown  precipi- 
tate falls,  change  fluid  every  third  day.  On  the  tenth  or 
twelfth  day  transfer  to  chromic  and  nitric  fluid.  Change 
frequently  till  the  bone  is  soft.  Then  place  it  in  methy- 
lated spirit.  The  cochlea  of  the  guinea  pig  projects  into 
the  tympanum,  and  is,  therefore,  convenient  for  enabling 
the  student  to  see  how  the  cone  is  to  be  sliced  when  sec- 
tions are  made. 

Too  long  exposure  to  chromic  acid  renders  tissues  friable, 
and  prevents  staining  with  carmine. 

Methylated  spirit  is  ordinary  alcohol  containing  10  per 
cent,  of  wood-naphtha,  and  is  used  in  England  as  a  substi- 
tute for  alcohol,  since  it  is  free  of  duty  for  manufacturing 
purposes. 


CHAPTER   XIII. 

THE   MICROSCOPE   IN   PATHOLOGY    AND  PRACTICAL   MEDICINE. 

PATHOLOGICAL  HISTOLOGY,  though  yet  imperfect,  has  at- 
tained an  extended  literature.  Paget,  Jones,  Sieveking, 
Rokitansky,  Virchow,  Rindfleisch,  and  Bill  roth  are  names 
of  investigators  in  this  department,  well  known  to  medi- 
cal students.  As  in  our  former  chapters,  we  aim  only  to 
present  the  briefest  and  most  elementary  outline  of  the 
subject  as  introductory  to  more  extended  research. 


THE    MICROSCOPE    IN    PATHOLOGY    AND    MEDICINE.     227 

I.  MICROSCOPIC  APPEARANCES  AFTER  DEATH  OF  THE 
TISSUES,  OR  NECROSIS. 

1.  Blood. — This  undergoes  decomposition  more  rapidly 
than  other  tissues.     The  colorless  corpuscle  or  bioplast, 
after  slightly  swelling,  dissolves,  and  entirely  disappears. 
The  coloring  matter  leaves  the  red  corpuscles  shortly  after 
death,  and  is  diffused  through  the  tissues,  then  the  cor- 
puscle disintegrates,  and  breaks  up  into  granules. 

2.  Nucleated  Cells. — In  these  the  protoplasm  coagulates, 
forming  a  solid  albuminate,  which  becomes  cloudy,  and 
breaks  up  into  granules. 

3.  Cell-membrane  resists  decomposition  in  proportion  as 
it  has  become  horny.     Hence  the  outer  layers  of  epithe- 
lium last  longer  than  the  inner  ones. 

o 

4.  Smooth  muscle  fibres  are  first  filled  with  dusty  parti- 
cles, which  unite  into  elongated  masses,  then  they  assume 
a  striated  appearance,  and  finally  soften  into  a  slimy  mat- 
ter. 

5.  Striated  Muscular  Fibre. — The  muscle-juice  coagu- 
lates to  a  solid  albumiuate,  giving  rise  to  rigor  mortis  in 
twelve  or  fourteen  hours  after  death,  except  in  death  from 
charcoal  or  sulphuretted  hydrogen  vapor,  lightning,  or 
from  putrid  fevers  or  long  debility.     This  stiffness  of  the 
muscle  lasts  about  twenty-four  hours.     Under  the  micro- 
scope the  transverse  strise  and  nuclei  first  disappear,  then 
fat-  and  pigment-granules  show  themselves,  the  fibres  melt 
away  from  the  edges  and  became  gelatinous.     If  gelatin- 
ous softening  is  marked,  the  fibres  may  disintegrate  into 
Bowman's  disks. 

6.  Nerve-tissue. — Little  is  known  of  its  necrosis,  beyond 
thelfact  that  the  white  substance  of  Schwann  first  coagu- 
lates, then  there  is  a  collection  of  drops  of  myelin  within 
the  neurilemma,   producing   varicosity  before   complete 
dissolution. 


228  THE    MICROSCOPIST. 

7.  Adipose  Tissue. — The  fluid  fat  leaves  the  cells  and 
gives  an  appearance  of  emulsion  to  the  mass. 

8.  Fibres  of  loose  connective  tissue  swell,  become  stained 
with  the  coloring  matter  of  blood,  granulate,  and  liquefy, 
or  they  may  desiccate  by  evaporation. 

9.  Elastic  fibres  and  networks  resist  longer  than  the  last. 
Hence  elastic  fibres  may  be  found  in  expectorated  matter 
from  gangrene  of  the  lungs,  etc.     Later,  they  break  into 
granular  striae,  then  into  molecules,  and  vanish. 

10.  Cartilage  resists  long,  but  melts  away  at  the  edge, 
first  becoming  transparent  and  reddish.     The  cells  fill' 
with  fat-globules  from  fatty  degeneration  of  bioplasm. 

11.  Bone  retains  its  structure  in  necrosis,  and  hence  is 
recognized  by  the  surgeon  in  sequestrse,  yet  it  decays  in 
patches.    The  bioplasm  becomes  flat  in  the  cells,  acid  fluids 
dissolve  the  lime  salts,  and  the  remaining  structure  disin- 
tegrates like  cartilage. 

The  ichorous  fluid  into  which  all  tissues  are  resolved, 
finally  ends  in  carbonic  acid,  ammonia,  and  water,  but 
the  metamorphic  substances  resulting  from  the  various 
preceding  changes  are  not  yet  well  known  to  histo-chem- 
istry.  Some  of  them  are  volatile,  sometimes  giving  rise 
to  emphysematous  or  crepitant  gangrene,  and  are  of  bad 
odor ;  others  are  more  solid,  and  produce  interesting  mi- 
croscopic objects,  as  leucin,  ty rosin,  margarin,  ammonio- 
magnesian  phosphate,  and  pigment-granules.  At  page 
135  we  have  referred  to  the  presence  of  bacteria  and  vib- 
riones,  and  their  origin  from  fungi,  in  decaying  animal 
matters. 

II.  MORBID  ACTION  IN  TISSUES. 

1.  Infiltration. — This  consists  in  the  deposition  or  filtra- 
tion of  material  from  the  blood,  and  is  caused  by  adultera- 
tion of  the  blood  or  certain  peculiarities  of  tissues.  Thus 
for  infiltration  of  fat,  the  liver  and  areolar  connective 
tissue  is  most  fitted;  for  superfluous  salts  of  lime,  the 


THE    MICROSCOPE    IN    PATHOLOGY    AND    MEDICINE.     229 

lungs ;  amyloid  matter  seeks  first  the  kidneys,  next  the 
spleen,  liver,  etc.  In  addition,  there  may  be  local  causes, 
as  pigment  deposits  from  hypereemia,  hemorrhage,  etc. 

(1.)  Amyloid  infiltration  of  tissues.  This  is  a  waxy, 
lardaceous,  or  vitreous  albuminate,  but  may  be  distin-" 
guished  from  fibrin,  albumen,  etc.,  by  becoming  blue, 
violet,  or  red,  with  iodine.  Sometimes  it  has  concentric 
layers.  Its  likeness  to  starch  led  Virchow  to  call  it 
amyloid. 

Deposits  of  fibrin  in  blood  extravasations  in  the  lungs 
show  a  change  into  amyloid,  round,  small  heaps  of  blood- 
globules,  fragments  of  tissue,  particles  of  charcoal,  etc. 

An  amyloid  infiltrated  cell  is  larger  than  natural,  and 
deformed,  often  coalescing  with  others. 

The  small  arteries  and  capillaries,  as  the  Malpighian 
tufts  of  the  kidney,  etc.,  are  generally  the  first  to  suffer 
infiltration,  which  extends  to  the  outer  coat  and  surround- 
ing tissue  of  the  artery,  even  obliterating  it.  The  degen- 
eration of  vessels  leads  to  anaemia,  as  in  lardaceous  liver. 

(2.)  Calcification  is  the  infiltration  of  tissue  with  solid 
phosphate  and  carbonate  of  lime.  Free  carbonic  acid  is 
the  solvent  of  these  salts,  and  by  its  capacity  for  diffusion 
it  escapes,  leaving  the  insoluble  salts  in  the  stagnating 
nutritive  fluid.  Thus  cartilage  becomes  bone,  and  under 
peculiar  circumstances  other  tissues  calcify,  as  the  pleu- 
ritic false  membrane,  etc. 

(8.)  Pigmentation.  Under  necrosis  we  referred  to  col- 
oring matter  of  the  blood  impregnating  tissues  in  soluble 
form ;  under  this  head  we  refer  to  it  in  solid  form,  as 
granules  or  particles,  often  without  much  depreciation  of 
the  functions  of  a  part.  The  color  of  bile  is  derived  from 
blood,  and  jaundice  is  an  infiltration  of  fluid  pigment  from 
absorption  of  bile  color.  The  black  pigment  of  the  lungs 
is  from  charcoal  or  inhaled  carbon.  Amoeboid  cells  or 
leucocytes  may  imbibe  solid  particles  and  carry  them  in 
their  wanderings. 


230  THE    MICROSCOPIST. 

(4.)  Fatty  infiltration.  This  is  different  from  fatty 
metamorphosis,  which  is  so  common  that  infiltration  may 
be  presumed  to  be  frequent.  In  fatty  metamorphosis  the 
globules  are  more  numerous,  but  do  not  run  together  as 
in  infiltration.  The  presence  of  soda  compounds  of  bile 
ill  the  blood,  forming  an  emulsion  with  fat,  may  lead  to 
infiltration,  as  chyme  yields  it  in  the  intestine,  or  as  liver- 
cells  absorb  it  from  the  serum  of  the  blood.  Fat  is  some- 
times removed  from  one  place  by  metastasis  to  be  depos- 
ited in  another. 

2.  Degeneration. — (1.)  Fatty  degeneration  is  a  meta- 
morphosis of  the  bioplasm,  marked  by  fat-globules  in  its 
interior.  Thus  in  dropsy  of  the  pericardium  the  epithe- 
lial cells  first  exhibit  fat-globules,  which  by  their  aggre- 
gation in  the  albuminous  matter  enlarge  the  cell  into  a 
globular  mass  of  granules.  Grluge  first  called  these  "  in- 
flammatory corpuscles,"  but  they  are  now  known  as  fatty 
degenerated  epithelium  or  granular  corpuscles.  These 
disintegrate  to  a  fatty  detritus.  A  large  amount  of 
granular  corpuscles  give  the  suspending  fluid  a  yellowish 
color.  The  appearance  of  colostrum,  on  the  first  secre- 
tion of  the  mammae,  is  due  to  this.  By  standing,  it  sepa- 
rates into  a  serous  fluid  and  cream-like  mass,  the  latter 
consisting  of  granular  (colostrum)  corpuscles. 

The  last  act  of  fatty  degeneration  may  be  termed  lacti- 
fication.  At  the  beginning  of  disintegration  the  Bruno- 
nian  movement  may  be  observed.  Fats  are  finally  partly 
saponified  and  partly  separated  in  solid  form,  rnargarin 
and  cholesterin. 

In  fatty  degeneration  of  muscle  we  observe  varicose 
fibrils  or  detritus,  which  render  the  strise  indistinct,  or 
fill  the  sarcolemma  with  fluid. 

Fatty  metamorphosis  is  the  regular  mode  of  decompo- 
sition for  tissues  liable  to  rapid  change,  especially  epithe- 
lium. Decreased  nutrition  may  produce  it,  especially  in 
non-vascular  tissues,  as  in  the  cells  of  laryngeal  cartilage, 


THE    MICROSCOPE    IN    PATHOLOGY    AND    MEDICINE.     231 

and  in  arcus  senilis.  Of  vascular  organs,  the  muscular 
tissue  of  the  heart  is  most  liable  to  it. 

The  cheesy  degeneration  of  Virchow  is  a  variety  of 
fatty  degeneration.  It  is  a  yellowish,  compact,  friable, 
or  smeary  mass,  like  cheese.  It  was  formerly  believed  to 
be  the  product  of  tuberculosis,  and  regarded  as.  the  sepa- 
ration of  morbid  matter  (crude  tubercle)  from  diseased 
blood.  It  is  now  regarded  as  a  fatty  degeneration  prod- 
uct, with  less  water  present  than  usual.  Sometimes  salts 
of  lime  are  infiltrated  in  such  masses.  Real  tubercle  is  a 
gray,  translucent,  compact  nodule,  about  the  size  of  a 
millet-seed  (miliary),  found  in  great  numbers  together. 
Cheesy  inflammation  and  miliary  tuberculosis  are  often 
found  side  by  side,  and  Oohnheim,  etc.,  have  shown  that 
inoculation  with  cheesy  detritus  will  produce  tubercle. 
Tubercle  is  found  in  many  organs,  especially  the  lungs. 
Its  structure  consists  of:  1.  Large  rounded  cells  of  finely 
granular  substance,  and  small  strongly-shining  nucleus 
or  nuclei.  2.  Small  cells,  with  shining,  darkly-contoured 
nuclei.  3.  Mother-cells,  with  'clear  areas  round  the  small 
ones.  4.  A  fine  fibrous  network  (Plate  XXV,  Fig.  182). 

(2.)  Mucoid  softening.  Mucus  is  a  colloid  substance, 
capable  of  swelling  by  imbibition,  but  of  little  capacity 
for  diffusion.  It  is  a  local  production  from  epithelia  of 
mucous  membrane,  yet  is  a  structural  element  in  many 
tumors.  In  the  foetus,  the  entire  subcutaneous  cellular 
tissue  is  mucous  tissue.  The  fibrinous  pseudo-membranes 
of  the  respiratory  organs  soften  by  mucoid  metamorpho- 
sis, and  in  cartilage  the  intercellular  substance  dissolves 
in  the  same  way,  producing  fibres  near  the  surface. 

(3.)  Colloid  degeneration.  This  is  similar  to  the  last, 
but  differs  in  having  peculiar  cells,  colloid  globules,  begin- 
ning in  a  normal  cell  by  a  change  in  its  bioplasm,  while 
mucoid  softening  occurs  between  the  fibres  of  connective 
tissue.  Like  mucus,  colloid  enlarges  by  imbibition,  and 
ends  in  soda  albuminate.  more  soluble  than  common  albu- 


232  THE    MICROS€OPIST. 

men,  and  identical  with  casein.  Thus  we  have  in  the 
living  and  dead  cell  a  circle  of  metamorphoses,  from  casein 
of  milk  to  albumen  of  blood,  thence  to  bioplasm,  to  formed 
material  of  cells  and  of  intercellular  substances,  to  mucus 
or  colloid,  and  finally  to  casein. 

III.  NEW  FORMATIONS. 

To  the  surgeon  the  most  important  of  these  are  tumors, 
excrescences,  hypertrophies,  or  overgrowths.  The  nomen- 
clature of  such  growths  is,  however,  greatly  redundant 
and  often  confusing.  Some  are  named  from  the  character 
of  their  contents  as  apparent  to  the  eye,  as  hygroma  (like 
water),  melanoma  (black  pigment),  chloroma  (green  ditto), 
hsematoma  (blood),  colloma  (glue),  steatoma  (lard),  athe- 
roma  (gruel),  meliceroma  (honey),  cholesteatoma  (cho- 
lesterin),  sarcoma  (flesh),  neuroma  (nerve),  encephaloma 
(brain),  myeloma  (marrow),  schiroma  (marble),  etc. 

Paget  classified  tumors  as  follows  : 

I.  Innocent. 

1.  Cystic:  Simple,  compound,  proliferous. 

2.  Solid:  Fatty,  fibro-cellular,  fibrous,  fibroid,  cartilag- 
inous, myeloid,  osseous,  glandular,  and  vascular. 

II.  Malignant:  Infiltrating,  ulcerating,  multiplying. 

Yirchow's  nomenclature  is  based  on  the  divisions  of 
hypertrophy,  homeoplastic  formations,  and  heteroplastic 
formations. 

Histologically,  the  questions  of  origin  and  structure 
chiefly  concern  us.  Such  a  study  may  yet  lead  to  a  true 
classification  and  rules  of  diagnosis.  Yirchow  held  that 
cells  multiply  by  division  at  the  place  of  the  tumor,  so 
that  the  newly-formed  tissues  substitute  a  certain  amount 
of  normal  constituents.  Cohnheim's  wandering  cells,  how- 
ever, show  that  formative  elements  may  come  from  a  dis- 
tance, although  local  formation  is  also  possible.  Strieker 
shows  in  inflammation  a  division  of  both  wandering  and 


THE    MICROSCOPE    IN    PATHOLOGY    AND    MEDICINE.     233 

local  cells.  This  favors  Beale's  view  that  multiplying 
bioplasm  are  the  true  disease  germs. 

The  general  plan  on  which  new  formations  occur  has 
been  shown  by  Rindfleisch  as :  1.  The  uniform  enlargement 
of  an  organ  by  increase  of  structural  elements  (hypertro- 
phy). 2.  A  node,  or  roundish  tumefaction,  by  interstitial 
deposit,  stretching  the  parenchyma.  3.  Infiltration,  which 
condenses  tissue  in  small  depots.  4.  Desquamation,  as  in 
epithelial  catarrh.  5.  Flat  tumefaction.  6.  Tuberosity, 
which,  when  narrow  or  finger-like,  is  a  papillae  or  wart. 
7.  Fungus,  spongy  or  ulcerated.  8.  Polypus,  a  papilla 
with  a  narrow  base.  9.  Dendritic  vegetation,  or  new 
papillae  from  the  sides  of  others.  10.  Cysts  of  retention, 
from  occlusion  of  ducts.  11.  Exudation  cysts,  in  closed 
cavities.  12.  Etravasation  cysts.  13.  Softening  cysts. 

Histologically,  we  may  divide  tumors  into : 

I.  Histoid,  whose   elements   correspond   with   normal 
tissues. 

II.  Carcinomatous,  dependent  on  abnormal  growth  of 
epithelial  elements.     These  are  generally  in  the  skin,  the 
mucous  membranes,  or  glands. 

The  following  list,  after  Billroth,  may  serve  for  brief 
reference : 

1.  Fibroma^  composed  of  developed  connective  tissue. 
(1.)  Soft  fibrous  tumors,  almost  exclusively  in  the  skin. 
(2.)  Firm  fibroma.     Most  often  in  the  uterus,  where  they 
may  calcify  or  form  fibrous  polypi;  sometimes  on  the 
periosteum  and  on  nerves. 

2.  Lipoma,  or  fatty  tumor. 

3.  Chondroma  (cartilaginous).     These  occur  on  bones, 
are  vascular,  and  often  ossify.     The  softened  and  cystic 
forms  have  been  called  colloid  tumors,  gelatinous  cancer, 
etc. 

4.  Osteoma  (exostosis).     These  may  be  spongy  or  com- 
pact. 

5.  Myoma.     Billroth  doubts  if  true  muscular  tumors 


234  THE    MICROSCOPIST. 

exist.     He  objects  to  calling  the  spindle-celled  fibroma  of 
the  uterus  myoma. 

6.  Xeuroma  (nerve  tumor).     This  also  is  misapplied  to 
all  tumors  or  nerves,  many  of  which  are  fibroma. 

7.  Angioma  (vascular  tumor),  as  nsevi  and  erectile  tu- 
mors.    They  may  be  plexiform  or  cavernous. 

8.  Sarcoma,  a  large  and  uncertain  group,  containing  (1) 
granulation  sarcoma,  or  round-celled  sarcoma  of  Virchow 
(Plate  XXY,  Fig.  183).     (2.)  Spindle-celled  sarcoma  (Plate 
XXV,  Fig.  184).     (3.)  Giant-celled  sarcoma  (Plate  XXY, 
Fig.  185).    (4.)  Net-celled  or  mucous  sarcoma  (Plate  XXY, 
Fig.  186).     (5.)  Alveolar  sarcoma,  often  resembling  carci- 
noma (Plate  XXY,  Fig.  187).     (6.)  Pigmentary  sarcoma, 
or  melanoma  (Plate  XXY,  Fig.  188). 

9.  Lymphoma,  or  enlarged  lymph-glands. 

10.  Papilloma,  or  hypertrophied  papillae. 

11.  Adenoma,  or  glandular  hypertrophy,  as  in  goitre ; 
sometimes  forming  mucous  polypi. 

12.  Cystic  tumors.     If  in  connection  with  other  tumors 
they  are  named  accordingly,  as  cysto-fibroma,  etc.     They 
may  be  simple,  compound,  or  proliferous. 

13.  Carcinoma,  or  cancers,  so  called  from  the  distended 
veins  sometimes  appearing  as  crabs'  feet. 

The  old  division  of  cancers  was  into  scirrhus  or  hard 
cancer,  the  outline  well  defined,  the  aspect  of  cut  surface 
glistening,  and  yielding  no  juice ;  colloid,  or  soft  cancer  ; 
encephaloid,  or  brain-like,  yielding  a  milky  juice  full 
of  cells  and  nuclei,  generally  soft,  affecting  neighboring 
glands,  and  associated  with  cancerous  cachexia;  fungus 
hsematodes,  when  protruding  and  bleeding.  Billroth 
treats  of  cancers  (1)  of  skin,  a  glandular  ingrowth  of  the 
rete  Malpighi,  and  showing  globular  cells.  (2.)  Mam- 
mary cancers.  (3.)  Of  mucous  membranes  with  cylindric 
epithelium.  (4.)  Of  lachrymal,  salivary,  and  parotid 
glands.  (5.)  Of  the  thyroid  gland  and  ovary. 

It  was  thought  by  the  early  microscopists  that  a  pecu- 


PLATE  XXV 


FIG.  182. 


Granulation  Sarcoma. 
FIG.  184. 


Spindle-celled  Sarcoma. 
FIG.  185. 


Giant-celled  Sarcoma,  with  ossifying  foci. 
FIG.  186. 


Alveolar  Sarcoma. 
FIG.  188. 


Pigmentary  Sarcoma. 
FIG. 189. 


Epithelial  Cancer  of  the  Cheeks. 
Ingrowth  of  the  rete  Malpighi. 


FIG.  190. 


Epithelial  Cancer  of  the  Stomach. 
FIG.  191. 


Net-celled  Sarcoma.. 


Soft  Glandular  Cancer. 


THE    MICROSCOPE    IN    PATHOLOGY    AND    MEDICINE.      235 

liar  caudate  cell  was  characteristic  of  cancer,  but  constant 
research  has  shown  that  there  is  no  special  form  of  cell 
in  this  disease.  The  greater  number  of  cancers  may  be 
characterized  as  a  proliferation  and  ingrowing  of  epithe- 
lial elements,  either  of  the  surface  or  of  the  glands.  Figs. 
189  to  191,  Plate  XXY,  illustrate  several  varieties  of 
carcinoma. 

The  anomalies  of  the  various  tissues  and  organs  are 
well  delineated  by  Rindfleisch  in  his  Pathological  Histology. 

IV.  MICROSCOPIC  EXAMINATION  OF  URINARY  DEPOSITS. 

Healthy  urine  holds  in  solution  a  variety  of  organic  and 
inorganic  substances,  as  urea,  uric  acid,  alkaline  and  earthy 
salts,  animal  extractive,  vesical  mucus,  and  epithelial  de- 
bris. A  few  drops  allowed  to  evaporate  on  a  glass  slide 
will  exhibit  the  crystalline  matters,  consisting  of  urea, 
urate  of  soda,  chloride  of  sodium,  phosphates  and  sul- 
phates. 

The  amount  passed  each  twenty-four  hours  varies  from 
20  to  50  ounces,  holding  in  solution  from  600  to  700  grains 
of  solid  matter.  Of  this,  about  three-fourths  consists  of 
organic,  and  one-fourth  of  saline  substances,  the  largest 
amount  being  urea,  comprising  nearly  two-thirds  of  the 
whole.  The  amount,  both  of  solids  and  fluids,  is  subject 
to  great  variation,  according  to  the  amount  of  fluids  im- 
bibed, the  action  of  the  skin,  etc. 

The  average  specific  gravity  of  healthy  urine  is  1.020. 
It  may  be  measured  with  the  urinometer,  a  loaded  glass 
bulb,  with  a  graduated  stem.  According  to  a  table  cal- 
culated by  Dr.  G.  Bird,  after  Dr.  Christisori's  formula, 
each  degree  of  the  urinometer  represents  2.33  grains  of 
solids  in  1000.  Thus  the  specific  gravity  1.020  represents 
46.60  grains  of  solid  matter  in  1000  of  urine.  By  weigh- 
ing all  the  urine  passed  in  twenty-four  hours,  it  is  easy, 
therefore,  to  calculate  the  amount  of  solids  secreted. 


236  THE    MICROSCOPIST. 

Dr.  Bird  has  also  given  another  table,  from  which  it 
appears  that  the  figures  of  specific  gravity  will  indicate 
nearly  the  amount  of  solids  in  each  fluid  ounce.  Thus, 
specific  gravity  1010  shows  a  little  more  than  10  grains 
of  solids  to  the  ounce ;  1020  equals  a  little  over  20  grains ; 
above  1030  a  grain  or  two  more  must  be  added,  as  1030 
equals  31 J  grains  ;  1035  gives  about  37  grains. 

The  proportion  of  urinary  excretion  to  the  weight  of 
the  body  is  often  an  important  consideration.  It  may  be 
stated,  as  an  average,  to  consist  of  about  149  grains  of 
water  and  6J  grains  of  solids  to  each  pound  weight  in 
twenty-four  hours. 

The  tables  given  by  different  observers  vary,  but  the 
above  may  serve  as  an  average  approximation. 

Urea  is  the  vehicle  by  which  nearly  all  the  nitrogen  of 
the  exhausted  tissues  is  removed  from  the  system,  and  its 
retention  is  often  attended  with  fatal  ursemic  poisoning  of 
the  blood.  In  health,  400  to  500  grains  are  excreted  in 
twenty-four  hours,  but  in  some  cases  of  kidney  diseases 
not  more  than  100  grains  are  eliminated,  while  in  some 
fevers  over  1000  grains  are  removed  in  the  same  period. 
If  urea  be  suspected  in  excess,  a  drop  of  urine  added  to  a 
drop  of  nitric  acid  may  be  placed  under  the  microscope, 
when  the  characteristic  crystals  of  nitrate  of  urea  will 
appear  (Plate  XXVI,  Fig.  192). 

Volumetric  analysis  is  the  best  means  of  ascertaining 
the  quantity  of  urea,  as  of  other  chemical  ingredients,  but 
the  practitioner  may  approximately  estimate  by  weighing 
the  crystals  of  nitrate  of  urea  formed  by  adding  nitric 
acid  to  double  the  quantity  of  urine,  which  has  been  con- 
centrated to  half  its  bulk  by  boiling. 

The  proportion  of  uric  acid  varies  from  0.3  to  1  part  in 
1000  of  healthy  urine.  It  may  be  obtained  by  adding  a 
few  drops  of  hydrochloric  acid  to  urine  concentrated  to 
half  its  bulk,  and  allowing  it  to  stand  in  a  cool  place. 

The  estimation  of  the  chlorides  in  urine  is  sometimes 


THE    MICROSCOPE    IN    PATHOLOGY    AND    MEDICINE.     237 

necessary  in  disease.  It  may  be  done  by  acidulating  the 
urine  with  a  few  drops  of  nitric  acid,  and  then  adding 
nitrate  of  silver.  The  precipitate  should  then  be  dried 
and  fused  in  a  porcelain  capsule  before  weighing. 

Albumen  in  suspected  urine  may  be  tested  by  boiling  in 
a  test-tube,  when  it  will  be  coagulated.  As  a  white  pre- 
cipitate sometimes  occurs  from  an  excess  of  earthy  phos- 
phates, a  few  drops  of  nitric  acid  should  be  added,  which 
dissolves  phosphates,  but  coagulates  albumen. 

Diabetic  sugar  is  recognized  by  several  tests.  Moore's 
test  is  made  by  mixing  the  urine  with  half  its  bulk  of 
liquor  potassae,  and  boiling  gently  for  five  minutes.  Sugar 
gives  the  liquid  a  brown  or  bistre  tint.  Trommer's  test 
consists  in  boiling  the  urine  with  a  mixture  of  caustic 
potash  and  sulphate  of  copper,  when  if  sugar  be  present 
the  suboxide  of  copper  will  be  reduced  to  a  reddish-brown 
or  ochre-colored  powder.  Fehling's  test  solution  is  a 
modification  of  the  last,  and  is  made  by  dissolving  69 
grains  of  sulphate  of  copper  in  345  grains  of  distilled 
water;  to  this  is  added  a  concentrated  solution  of  268 
grains  of  tartrate  of  potash,  and  then  a  solution  of  80 
grains  of  carbonate  of  soda  to  1  ounce  of  water,  and  the 
whole  diluted  to  1000  grains.  The  fermentation  test 
consists  in  filling  a  test-tube  with  urine,  to  which  a  little 
yeast  is  added.  The  tube  is  then  inverted  over  a  saucer 
containing  a  little  urine,  and  placed  in  a  warm  place  for 
twenty-four  hours.  If  sugar  is  present,  it  undergoes 
vinous  fermentation,  yielding  alcohol  and  carbonic  acid. 
The  latter  rises  in  the  tube  and  displaces  the  liquid. 

The  coloring  matter  of  bile  in  urine  may  be  detected  by 
the  nitric-acid  test.  A  few  drops  of  biliary  urine  are 
poured  on  a  white  plate,  and  a  drop  of  nitric  acid  allowed 
to  fall  upon  it.  As  the  acid  mixes  with  the  fluid,  a  play 
of  colors,  commencing  in  green,  passing  through  various 
shades,  and  terminating  in  red,  will  be  observed. 

We  necessarily  omit  many  chemical  details  respecting 


238  THE    MICROSCOPIST. 

urinary  examinations,  but  the  foregoing  will  be  found  of 
practical  use  to  the  student. 

Microscopic  deposits  in  urine  are  either  organic  fixtures 
or  precipitates  from  solution.  They  should  be  collected 
by  standing  several  hours  in  a  conical  vessel. 

1.  Organic  Mixtures. — (1.)  Epithelium.  The  character 
of  the  scales  will  serve  often  to  show  the  locality  of  dis- 
ease in  the  urinary  organs.  The  appearance  of  cells  from 
various  parts  is  shown  in  Fig.  142. 

(2.)  Mucus  and  pus-cells.  Mucus  is  deposited  as  a  floc- 
culent  cloud,  entangling  a  few  round  or  oval  delicately 
granular  cells,  a  little  larger  than  a  red  blood-globule. 
In  disease  this  increases  and  contains  numerous  ill-defined 
cells.  A  very  thick  glairy  deposit  in  disease  of  the  blad- 
der may  be  mistaken  for  mucus,  although  it  is  pus  altered 
by  the  action  of  carbonate  of  ammonia. 

As  pus  is  often  formed  from  the  germinal  matter  of 
epithelial  cells,  a  small  quantity  in  the  urine  is  not  neces- 
sarily a  sign  of  serious  disease.  In  large  quantities,  pus 
forms  an  opaque  cream-colored  deposit,  which  becomes 
glairy  and  tenacious  on  the  addition  of  liquor  potassse. 
Pus-globules  under  the  microscope,  if  long  removed  from 
the  body,  are  granular,  and  show  from  one  to  four  nuclei 
when  treated  with  acetic  acid.  In  fresh  pus-corpuscles, 
especially  in  warm  weather,  amoeboid  motion  is  often  seen. 
In  a  late  period  of  catarrh  of  the  bladder,  but  little  epi- 
thelium will  accompany  the  discharge,  but  crystals  of 
triple  phosphates  generally  occur  in  pus  derived  from  the 
bladder. 

(3.)  Blood-disks  usually  form  a  reddish-brown  deposit. 
A  smoky  appearance  of  the  urine  is  produced  in  blood 
derived  from  the  kidney.  A  brown  deposit  resembling 
blood,  but  showing  granules  and  no  disks,  is  supposed  to 
be  derived  from  blood.  The  epithelium  associated  with 
blood-disks  will  often  point  out  the  source  of  haemorrhage. 

(4.)  Spermatozoa  in  urine  are  not  uncommon  in  perfect 


PLATE  XXVI. 


FIG.  192. 


FIG. 193. 


ff// 


Tube-casts. 


Nitrate  of  Urea. 


FIG.  194. 


FIG.  195. 


Urate  of  Ammonia. 


FIG.  196. 


Uric  Acid. 


0 


Uric  Acid. 


FIG.  197. 


o 


f-7     „, 


Uric  Acid— re-precipitated. 


THE    MICROSCOPE    IN    PATHOLOGY    AND    MEDICINE.     239 

health,  but  nervous  patients  are  often  deluded  by  quacks 
on  account  of  them. 

(5.)  Accidental  products.  A  great  variety  of  things 
may  accidentally  get  into  urine,  and  the  observer  must 
guard  against  them  by  studying  the  appearance  of  various 
objects  in  the  microscope.  Pieces  of  feathers,  fibres  of 
wood,  vegetable-cells,  wool,  cotton,  silk,  dust,  etc.,  will 
almost  always  attract  the  attention  first  of  one  unused  to 
them. 

(6.)  Sarcinse  are  minute  vegetable  organisms,  in  the 
form  of  cubes,  often  subdividing  into  groups  of  four  or 
their  multiples.  They  were  detected  by  Goodsir  in  the 
stomach  in  a  case  of  obstinate  vomiting,  and  have  been 
occasionally  found  in  urine.  They  seem  associated  with 
some  dyspeptic  cases. 

(7.)  Torulce.  This  fungus  is  developed  in  urine  which 
contains  even  minute  traces  of  sugar.  It  is  identical  with 
the  yeast  plant  (see  pages  135,  137). 

(8.)  The penicillium  glaucum,  a  fungus  allied  to  the  last, 
commonly  makes  its  appearance  in  acid  urine  when  ex- 
posed to  the  air. 

(9.)  Yibriones.  What  was  said  at  page  135  will  readily 
account  for  the  presence  of  vibriones  in  decaying  urine. 
In  perfectly  fresh  urine  it  may  be  regarded  as  a  sign  of 
debility. 

(10.)  Tube-casts.  In  many  cases  of  congestion  and  in- 
flammation a  coagulable  material  is  effused  into  the  tubes 
of  the  kidney,  forming  a  cast  or  mould  of  the  tube.  This 
may  be  ejected,  bringing  with  it  pus,  blood,  epithelium, 
or  other  material  with  which  it  is  associated.  In  Bright's 
disease  these  casts,  in  addition  to  albuminous  urine,  as- 
sume considerable  clinical  importance.  In  the  acute  form 
of  the  disease  the  cylinders  or  casts  are  fibrinous,  with 
blood,  mucus  or  pus-cells,  and  epithelium.  Towards  the 
close  the  casts  become  homogeneous  or  hyaline.  In  chronic 
desquamative  nephritis  the  cylinders  are  without  blood, 


240  THE    MICROSCOPIST. 

and  towards  the  close  waxy  or  fatty,  often  containing 
many  oil-globules  (Plate  XXVI,  Fig.  193). 

2.  Precipitates  from  Solution. — (1.)  Urate  of  ammonia. 
This  is  generally  an  amorphous  deposit,  in  irregular  groups 
of  molecules,  but  with  an  alkaline  fermentation  sometimes 
crystallizes  (Plate  XXYI,  Fig.  194).  Some  regard  this 
as  urate  of  soda,  or  a  mixture  of  urates  of  potash,  soda, 
and  ammonia. 

Its  color  varies  from  light  pink  to  brickdust  color.  It 
is  deposited  in  all  concentrated  urine,  and  is  often  a 
"  critical  discharge  "  in  fevers,  etc.  It  is  found  in  gouty 
concretions,  and  dissolves  with  heat  and  acids. 

('!.}  Uric  acid  may  occur  from  an  acid  fermentation 
dissolving  urates  of  soda  or  ammonia.  It  is  a  yellow, 
reddish,  or  brown  sediment  of  crystals,  which  assume 
different  forms,  as  rhomboid  tablets  with  obtuse  angles, 
or  of  the  shape  of  a  whetstone  (Plate  XXVI,  Fig.  195). 

When  slowly  precipitated,  it  may  form  druses  of  four- 
sided  prisms  (Plate  XXYI,  Fig.  196).  When  precipitated 
from  fresh  urine  by  the  addition  of  muriatic  acid,  the 
crystals  are  large,  and  often  of  varying  shapes. 

They  may  be  tested  by  dissolving  in  potassa,  and  re- 
precipitating  by  muriatic  acid,  when  they  assume  the 
shape  of  Fig.  197,  Plate  XXYI. 

They  originate  from  waste,  excess  of  nitrogenous  food, 
defective  assimilation,  congestions  of  the  kidney ,  or  chronic 
disease  of  the  respiratory  organs. 

(3.)  Ammonio-phosphate  of  magnesia,  triple  phosphate, 
may  be  precipitated  from  fresh  urine  in  stellate  crystals 
(Plate  XXVII,  Fig.  198)  by  adding  ammonia.  When 
more  slowly  deposited  from  alkaline  urine,  or  in  diseased 
states  of  the  system,  the  crystals  are  prismatic,  generally 
triangular,  with  obliquely  truncated  ends.  Sometimes  the 
terminal  edges  are  bevelled,  and  the  varying  lengths  of 
the  prisms  give  rise  to  a  variety  of  forms  (Plate  XXVII, 
Fig.  199).  They  are  generally  thought  to  proceed  from 


PLATE  XXVII 


FIG.  198. 


• 


Ammonio-phosphate  of  Magnesia. 


FIG.  200. 


^—y/^ 
& 

Phosphate  of  Lime. 


FIG.  202. 


Ammonio-phosphate  of  Magnesia. 


FIG.  201. 


cP 


Chloride  of  Sodium. 


Oxalate  of  Lime. 


FIG.  203. 


*>0 

00 


0 


Cystine. 


FIG.  204. 


Salivary  corpuscles,  epithelial  scales  and  granul( 


THE    MICROSCOPE    IN    PATHOLOGY    AND    MEDICINE.     241 

disintegrated  albuminous,  and  chiefly  nervous,  matter,  but 
their  clinical  importance  is  not  fully  settled.  They  are 
found  in  cases  of  nervous  depression,  various  forms  of 
dyspepsia,  shock  of  the  spinal  cord,  irritation  of  the  blad- 
der, etc. 

In  highly  alkaline  urine,  the  triple  phosphates  are 
usually  accompanied  with  pus  and  phosphate  of  lime. 
The  latter  occurs  as  minute  granules  or  dumb-bells,  or  in 
groups  of  crystals  (Plate  XXVII,  Fig.  200). 

(4.)  Oxalate  of  lime  is  deposited  in  small  octahedra, 
generally  appearing  under  the  microscope  as  minute 
squares,  with  crossed  lines  proceeding  from  the  angles, 
the  upper  angle  being  next  the  eye  (Plate  XXVII,  Fig. 
201).  Dumb-bell  forms,  and  circular  or  oval  crystalline 
masses,  are  often  seen. 

Oxalate  of  lime  is  found  as  a  urinary  deposit  in  various 
conditions,  as  pulmonary  and  dyspeptic  affections.  It  is 
usually  associated  with  hypochondriasis,  and  in  cases  of 
overfatigue,  particularly  from  mental  work,  it  is  very 
common.  Its  association  with  calculous  affections  ren- 
ders it  interesting  to  the  surgeon. 

(5.)  Chloride  of  sodium  never  crystallizes  from  fluid 
urine.  On  evaporation  it  crystallizes  in  stellar  form  or 
in  cubes  (Plate  XXVII,  Fig.  202).  The  presence  of  urea 
sometimes  disposes  it  to  assume  the  form  of  a  regular 
octahedron. 

It  is  useful  to  investigate  this  excretion  in  typhoid 
fevers  and  inflammations  of  the  respiratory  organs,  etc. 
In  commencing  hepatization  of  the  lung  it  is  absent,  but 
returns  on  resolution  of  the  inflammation.  The  method 
of  testing  has  been  given  before. 

(6.)  Cystin  (Plate  XXVII,  Fig.  203)  crystallizes  in 
characteristic  six-sided  plates.  It  contains  a  large  pro- 
portion of  sulphur,  26  per  cent.,  and  is  considered  a 
product  of  decomposition.  It  is  often  associated  with 

16 


242  THE    MICROSCOPIST. 

calculus.     Some  regard  it  as  indicating  a  strumous  and 
ill-nourished  system. 

V.  LIST  OF  PARASITES  INFECTING  THE  HUMAN  BODY. 

I.  Epiphytes,  or  vegetable  parasites.  Parasitic  lesions 
of  the  surface  are  denoted  by  the  infiltration  or  destruc- 
tion of  hairs  and  epithelial  textures  by  the  sporules  of  a 
fungus,  which  by  union  or  growth  form  elongated  branches 
or  mycelia.  Reference  has  been  made,  page  136,  to  poly- 
morphism, or  the  varieties  of  form  produced  by  the  same 
fungus  germ,  so  that  the  names  ascribed  to  these  parasites 
must  be  regarded  as  only  provisional.  The  diagnosis  of 
fungi  on  the  skin,  hair,  or  epithelium  requires  care  and 
skill  in  microscopic  manipulation,  and  the  use  of  liquor 
potassse  long  enough  to  render  the  specimen  transparent. 

1.  The  Trichopkyton  tonsurans,  present  in  ring-worm  of 
the  body,  scalp,  or   beard.     Its   anatomical   seat  is  the 
interior  of  the  roots  of  the  hairs,  but  it  also  covers  the 
epidermis  between  the  hairs,  and  invests  them  in  a  white 
sheath,  producing  inflammation  of  the  follicles  and  sur- 
rounding tissues,  and  subsequent  baldness. 

2.  The  Trichophyton  sporuloides,  present  in  the  disease 
called  plica  polonica. 

3.  Achorion  Sckonleinii  and  the  Pacciniafavi,  present  in 
the  honeycomb  ring-worm. 

4.  Microsporon  mentagraphyta,  present  in  the  Mentagra. 

5.  Microsporon  furfur,  the  cause  of  liver-colored  spots, 
or  Pityriasis  versicolor. 

6.  Microsporon  Audouini,  occurring  in  Porrigo  decal- 
vans$  or  bald  patches. 

7.  Mycetoma  Carteri,  the  cause  of  the  "  fungous  foot  of 
India/' 

8.  Oidium  albicans,  in  diphtheria  and  aphtha. 

9.  Cryptococcus  (or  Torula)  cerevisice,  yeast  plant  in  blad- 
der or  stomach. 


THE    MICROSCOPE    IN    PATHOLOGY    AND    MEDICINE.     243 

10.  Sarcina  ventricuH,  in  the  stomach. 

11.  Epizoa,  or  animals  living  upon  the  skin  and  hair. 

1.  Pediculus,  or  louse,  three  forms:  P.  corporis,  P.  capi- 
tis,  and  P.  pubis. 

2.  Acarus  scabiei,  or  itch  insect. 

3.  Demodex  folliculorum,  inhabiting  sebaceous  and  hair- 
follicles. 

III.  Entozoa,  or  internal  parasites.  On  page  171  we 
have  given  a  general  account  of  the  Entozoa.  At  least 
thirty  different  forms  have  been  described  as  infesting 
the  human  body ;  eight  species  of  Tcenia  and  two  of 
Hothriocephali,  genera  of  the  family  Cestoidea  or  tape- 
worms, of  which  the  Cysticerci  and  Echinococci  (vesicu- 
lar cysts  containing^  an  embryo  head  provided  with  a 
circle  of  booklets,  and  giving  rise  to  the  appearance  of 
measly  flesh  in  animals)  are  larval  forms;  nine  species  of 
Trematoda,  or  fluke-like  parasites,  existing  in  an  encysted 
and  a  free  state;  and  eleven  species  of  Nematoid,  or  round- 
worms,  including  the  common  round-worms  or  Ascaris, 
the  Trichina  spiralis,  and  the  Filaria  oculi,  etc. 

Students  who  have  not  access  to  Dr.  Cobbold's  great 
work  on  parasites,  may  find  an  excellent  resume  in  Dr. 
Ait  ken's  Science  and  Practice  of  Medicine. 

VI.  EXAMINATION  OF  SPUTA. 

The  microscopic  examination  of  sputa  is  important  in 
practical  medicine,  but  requires  familiarity  with  the  ap- 
pearance of  different  structures  under  different  magnify- 
ing powers,  as  fragments  of  food,  muscular  fibre,  starch, 
etc. 

We  may  usually  expect  to  find  mucus,  entangling  air- 
bubbles,  and  pavement-epithelium  from  the  mouth  (Plate 
XXVII,  Fig.  204).  In  catarrhal  affections,  ciliated  epi- 
thelium from  the  nasal  or  respiratory  passages  may  also 
be  seen,  and  perhaps  molecules  of  fat,  pus-globules,  blood, 


244  THE    MICROSCOPIST. 

or  transformed  epithelial  cells  (formerly  called  granule- 
cells,  or  inflammatory  corpuscles).  In  phthisis,  the  soft- 
ened tubercle  or  gangrene  may  be  early  detected  by  the 
fibres  of  elastic  tissue  from  the  walls  of  the  pulmonary 
vesicles.  The  sputa  should  be  first  liquefied  by  boiling 
with  an  equal  bulk  of  caustic  soda,  and  then  allowed  to 
settle  in  a  conical  glass,  when  a  small  quantity  may  be 
removed  by  a  pipette  to  a  glass  slide,  covered  by  thin 
glass,  and  placed  under  the  microscope. 

The  occurrence  of  fungi  in  sputa  is  to  be  expected 
whenever  there  is  decay.  The  Leptothrix  luccalis,  one 
form  of  Pendllium,  is  common  on  old  epithelial  scales  of 
the  mouth,  and  in  the  later  stages  of  phthisis  the  sputa 
will  often  show  fungi  in  different  stages  of  development. 
Bacteria  and  vibriones  are  also  frequent  in  pus. 

In  catarrhal  pneumonia  we  may  find  fibrinous  casts  of 
the  alveoli  of  the  lungs  and  epithelial  elements. 

VII.  HINTS  ON  THE  APPLICATION  OF  THE  MICROSCOPE  TO 
MATERIA  'MEDICA  AND  PHARMACY. 

The  observations  of  Dr.  Hassall  on  the  detection  of 
adulterations  in  food,*  have  prompted  similar  investiga- 
tions respecting  the  purity  of  medicinal  substances.  Such 
examinations  cover  a  wide  field  of  research,  chiefly  related 
to  micro-chemistry  and  botany. 

The  student  hi  this  department  will  do  well  to  provide 
himself  with  undoubted  specimens  of  various  articles  for 
comparison,  although  much  may  be  learned  from  a  gen- 
eral examination  of  any  particular  drug,  etc. 

In  addition  to  the  recognition  of  genuine  forms  of  leaves, 
seeds,  roots,  etc  ,  and  their  adulterations,  the  microscope 
will  often  be  serviceable  in  exhibiting  the  deteriorations 
to  which  such  articles  are  subject  if  kept  too  long. 

Dr.  Hale,  in  the  American  Journal  of  Microscopy,  shows 

*  Food  and  its  Adulterations.     By  A.  H.  Hassall,  M.D. 


THE    MICROSCOPE    IN    PATHOLOGY    AND    MEDICINE.     245 

that  various  causes  combine  to  effect  the  deterioration 
of  drugs.  They  may  become  infested  with  animalculee. 
Leaves  and  roots  may  be  eaten  by  insects  until  all  vestige 
of  medicinal  power  is  destroyed.  Fungi  of  various  kinds 
may  destroy  the  tissue.  The  uncertain  action  of  some 
pharmaceutical  preparations  may  be  thus  accounted  for. 

For  the  method  of  examination  in  this  department,  as 
well  as  in  medical  jurisprudence,  we  refer  to  the  foregoing 
chapters,  contenting  ourselves  here  with  the  remark,  that 
investigations  involving  life  or  reputation  should  never  be 
undertaken  without  a  thorough  practical  acquaintance 
with  microscopic  manipulation  and  the  microscopic  sci- 
ences. He  to  whom  such  work  is  intrusted,  should  be 
able  to  exhibit  and  to  explain  to  an  intelligent  jury  what 
he  has  seen  and  what  he  ought  to  see. 


LIBRARY 

UNIVERSITY  OF  1 

VLIFORNIA. 


GLOSSAEY. 


Aberration  (ab,  from,  and  <?rro,  to  wander). — The  errors 
resulting  from  the  imperfection  of  lenses.  They  are  of 
two  kinds,  chromatic  and  spherical  aberration. 

Abiogenesis. — The  dogma  of  spontaneous  generation,  or 
the  alleged  production  of  living  beings  without  pre-exist- 
ing germs. 

Absorption  Bands. — Transparent  substances  are  usually 
opaque  to  certain  colored  rays  of  light,  that  is,  absorb 
them ;  and  when  they  are  submitted  to  prismatic  analy- 
sis, this  opacity  causes  gaps  in  the  spectrum.  Some  sub- 
stances produce  absorption  lines  of  great  sharpness,  while 
others  have  an  indistinct  outline. 

Achromatic. — Destitute  of  chromatic  aberration. 

Alternation  of  Generations,  or  Metagenesis,  is  a  term  em- 
ployed to  designate  a  cycle  of  phenomena  in  which  one 
generation  does  not  produce  a  form  like  itself,  but  one 
whose  progeny  are  similar  to  the  generation  preceding. 

Ameboid  Movements. — Motion  in  minute  masses  of  bio- 
plasm, resembling  that  of  Amoeba.  It  has  been  recognized 
in  Yolvox,  in  Chara,  in  the  roots  of  mosses,  in  fungi,  as 
well  as  in  colorless  blood-cells. 

Amyloid  Infiltration. — A  filtration  of  waxy  or  lardaceous 
albumin  ate  from  the  blood  among  certain  tissues  of  the 
body. 

Angular  Aperture. — The  angle  made  by  the  diameter 
of  the  actual  aperture  of  an  objective  and  the  distance 


248  GLOSSARY. 

from  its  focal  point.  A  very  wide  angle  of  aperture  only 
allows  distinct  vision  of  what  is  exactly  in  focus,  so  that 
when  penetration  is  needed  most,  as  in  physiological  work, 
a  smaller  angle  is  better  than  one  used  for  resolution  of 
diatoms  and  other  minutiae. 

Aplanatic. — Destitute  of  spherical  aberration. 

Archeus. — The  term  applied  by  Van  Helmont  to  the 
specific  agent  which,  according  to  his  theory,  presided 
over  vital  functions. 

Bacteria. — Minute,  transparent,  rod-like  bodies,  some- 
times jointed,  and  often  exhibiting  a  vacillating  motion. 
It  is  probable  that  they  are  produced  by  the  germs  of 
fungi  in  a  solution  of  animal  matter. 

Bathybius. — A  term  given  by  Professor  Huxley  to  the 
slimy  matter  from  the  ocean  bottom.  Doubts  have  been 
expressed  as  to  its  animal  nature. 

Binocular  (binus,  two,  and  oculits,  an  eye). — An  ar- 
rangement of  a  prism  (Wenham's)  and  eye-pieces  for 
two  eyes,  so  as  to  produce  a  stereoscopic  effect  with  the 
microscope. 

Biology  (Gr.  Bios,  life,  and  logos,  a  discourse).  —  The 
study  of  living  beings,  including  zoology  and  botany. 

Bioplasm. — A  term  proposed  for  the  elementary  sub- 
stance of  organic  bodies  when  actually  alive,  or  living 
protoplasm. 

Blastema. — The  fluid  matter,  or  plasma,  in  which,  ac- 
cording to  the  theory  of  Schleiden  and  Schwann,  nuclei 
first  make  their  appearance,  and  then  organic  cells. 

Brunonian  Motion. — The  molecular  movement  of  fine 
particles  suspended  in  fluid,  first  observed  by  Dr.  R. 
Brown  in  1827. 

Calcification. — The  infiltration  of  animal  tissues  with 
salts  of  lime. 

Cell. — The  elementary  unit  of  organic  structure.  From 
the  time  of  Schleiden  and  Schwann  (1838)  the  researches 
of  biologists  have  been  greatly  aided  by  the  demonstra- 


GLOSSARY.  249 

tion  of  the  development  of  all  living  things  from  cells. 
A  cell-wall,  cell-contents,  and  a  nucleus,  were  formerly 
regarded  as  essential,  but  further  investigation  has  shown 
that  a  cell  is  essentially  a  semisolid  mass  of  living  matter. 

Chlorophyll. — The  green  coloring  matter  of  vegetables. 

Chromatic  Aberration. — The  errors  depending  on  the 
unequal  refrangibility  of  the  colored  rays  which  make  up 
white  light. 

Ciliary  Motion. — The  movement  of  cilia,  or  minute  hair- 
like  bodies,  on  animal  and  vegetable  cells.  The  cause  of 
it  is  unknown. 

Colloid. — Substance  devoid  of  crystalline  power,  as 
gum,  albumen,  gelatin,  etc.  Such  substances  pass  slowly 
through  a  membrane,  while  crystalloid  bodies  pass  readily, 
thus  enabling  us  to  separate  them  by  dialysis. 

Correlation  of  Forces. — The  doctrine  that  any  one  of 
the  forms  of  physical  force  may  be  converted  into  one  or 
more  of  the  other  forms. 

Cryptogamia. — Lower  orders  of  plants,  whose  fructi- 
fication does  not  depend  on  the  presence  of  stamens  and 
pistils  in  the  flower. 

Crystallography. — The  science  which  treats  of  the  laws 
by  which  the  surfaces  of  crystals  are  disposed  to  one 
another. 

Crystalloid. — Substances  capable  of  crystallization. 

Cydosis. — A  circulation  of  fluid  in  the  cells  of  plants. 

Definition. — The  power  of  an  object-glass  to  give  a  dis- 
tinct image  of  an  object. 

Diaphragm. — A  stop  for  intercepting  some  of  the  lu- 
minous rays,  generally  placed  just  beneath  the  micro- 
scope stage. 

Diffraction  of  Light. — A  disturbance  of  the  straight 
path  of  a  ray  of  light  from  its  passage  close  to  the  edge 
of  an  opaque  body. 

Double  Refraction. — The  power  possessed  by  some  crys- 
tals, as  Iceland  spar,  of  exhibiting  two  images.  The  po- 


250  GLOSSARY. 

lariscope  tests  this  property  and  exhibits  it  in  many  sub- 
stances. A  thin  film  of  selenite  intensifies  it  if  it  is  not 
strong  enough  to  show  color  otherwise. 

Epiphytes. — Parasitic  plants. 

Epithelium. — The  layer  or  layers  of  cells  covering  ex- 
ternal or  internal  surfaces  of  animal  bodies. 

Epizoa. — Parasitic  animals. 

Focal  Distance. — The  distance  from  the  centre  of  a  lens 
to  the  focus,  or  point  of  distinct  vision. 

Foraminifera. — Shells  of  minute  animals,  chiefly  calca- 
reous, which  are  perforated  with  minute  pores  for  the  pro- 
trusion of  threads  of  sarcode  or  bioplasm. 

Formed  Matter. — The  structure  produced  by  the  action 
of  bioplasm,  or  by  the  influence  of  external  agents  upon  it. 

Fraunhofer's  .Lines. — The  dark  lines  which  cross  the 
solar  spectrum,  corresponding  to  the  chemical  nature  of 
the  burning  substance.  The  blackness  of  the  lines  de- 
pends on  the  incandescent  vapor  of  the  substance. 

Gemmation,  or  Budding. — A  term  given  to  the  repro- 
duction of  cells  by  the  protrusion  of  a  part  of  their  sub- 
stance, which  becoming  constricted,  falls  oft'  and  lives  an 
independent  life. 

Germinal  Matter. — Another  name  for  bioplasm,  or  "  cell- 
stuff." 

Herapathite. — The  iodo-disulphate  of  quinia. 

Histo-Chemistry. — The  science  which  investigates  the 
chemistry  of  the  tissues. 

Histology. — The  science  of  tissues. 

Immersion  Lens. — An  objective  arranged  so  as  to  re- 
quire a  drop  of  fluid  interposed  between  its  front  lens 
and  the  covering  glass  of  the  object. 

Indifferent  Fluids. — Fluids  which  produce  little  or  no 
change  in  animal  or  other  tissues. 

Infiltration. — The  deposition  of  material  from  the  blood 
into  various  tissues. 

Lens. — A  piece  of  glass  ground  and  polished  so  as  to 


GLOSSARY.  251 

refract  the  light  to  a  focus,  or  causing  the  rays  to  di- 
verge. 

Leucocytes. — "White  cells,  whether  in  blood  or  elsewhere. 
They  are  simply  masses  of  bioplasm. 

Luteine  Spectra. — The  spectra  produced  by  light  passing 
through  juice  from  the  corpora  lutea  in  the  ovary. 

Metamorphosis. — Change  of  form,  as  from  the  caterpil- 
lar to  the  butterfly. 

Metric  Measure. — The  system  first  adopted  in  France, 
based  on  the  metre,  which  is  the  ten  millionth  of  the 
quadrant  of  the  meridian  of  Paris.  The  unit  of  surface 
is  the  arc  of  one  hundred  square  metres.  The  unit  of 
weight  is  the  gramme,  weighing  TTJluoth  of  a  cubic 
metre  of  water.  The  multiples  are  indicated  by  Greek 
prefixes,  deca  (10),  hecto  (100),  kilo  (1000),  myrio  (10,000). 
The  subdivisions  are  named  by  Latin  prefixes,  deci,  centi, 
arid  milli. 

Micro-gonidia.— Bodies  resulting  from  the  segmentation 
of  motile  cells  in  the  lower  order  of  vegetables.  When 
possessing  active  movement  they  rank  as  zoospores. 

Micrometer.  —  An  instrument  for  measuring  minute 
spaces. 

Microscopy. — The  use  of  the  microscope,  and  the  knowl- 
edge attained  by  it. 

Microzymes. — Minute  molecules  found  in  the  vaccine 
vesicles,  glanders,  and  other  disease  products. 

Molecular  Coalescence. — A  name  given  to  the  action  of 
various  chemical  substances,  in  a  nascent  state,  upon  an 
organic  colloid. 

Monera. — The  name  given  by  Professor  Hackel  to  the 
simplest  forms  of  animal  life. 

Morphology.  —  The  science  of  form.  Applied  to  the 
structures  of  organized  beings. 

Motile  Cells. — Minute  vegetable  cells,  moving  by  means 
of  vibratile  cilia.  After  a  time  they  lose  their  cilia  and 
become  still  cells,  which  multiply  by  self-division. 


252  GLOSSARY. 

Necrosis. — The  death  of  tissue. 

Nucleus. — A  concentration  of  vital  power  in  a  mass  of 
bioplasm. 

Objective. — The  object-glass  of  a  microscope. 

Oblique  Illumination. — The  illumination  of  microscopic 
objects  by  light  thrown  from  the  side,  either  by  the  mirror 
or  some  special  contrivance. 

Oolites. — Certain  rocks  which  present  a  granular  struc- 
ture resembling  the  roe  of  a  fish. 

Orbitolites. — Foraminiferous  shells  of  considerable  size 
occurring  in  tertiary  limestones. 

Otoliths. — Small  crystalline  bodies  from  the  inner  ear. 

Pabulum. — The  nutritive  material  supplied  to  animal 
cells. 

Parthenogenesis. — Reproduction  without  sexual  union. 

Pathology. — The  science  of  diseased  structure  and  func- 
tion. 

Penetration. — The  property  of  an  objective  which  ex- 
hibits layers  of  structure  below  the  focus.  It  seems  to 
depend  on  moderate  angular  aperture. 

Physical  Movements. — A  peculiar  vibratile  motion  in  mi- 
nute particles  suspended  in  fluid.  See  Brunonian  Motion. 

Polymorphism. — The  development  of  similar  germs  into 
different  forms  by  various  agencies. 

Protophytes. — Plants  of  simplest  forms. 

Protoplasm. — The  elementary  cell-material,  or  "physi- 
cal basis  of  life." 

Protozoa. — Simplest  forms  of  animals. 

Raphides. — Crystals  occurring  in  vegetable  tissues. 

Resolution. — The  property  in  a  microscope  of  exhibiting 
minute  details,  as  lines,  etc. 

Sarcode. — A  synonym  of  protoplasm,  or  cell-material. 

Sclerogen. — Woody  tissue. 

Selenite. — Crystallized  sulphate  of  lime. 

Spectrum  Analysis. — The  analysis  of  incandescent  sub- 
stances by  means  of  the  spectroscope. 


GLOSSARY.  253 

Spherical  Aberration. — The  errors  of  lenses  arising  from 
the  spherical  surface,  so  that  the  rays  from  centre  and 
edge  do  not  accurately  combine  in  focus. 

Spontaneous  Generation. — The  theory  of  the  spontaneous 
or  independent  origin  of  minute  organisms.  Bastian's 
views  in  favor  of  this  theory  seem  to  have  been  over- 
thrown by  the  experiments  of  Pastern  and  Tyndall,  and 
biologists  now  generally  agree  to  the  doctrine  that  all 
living  bodies  are  derived  from  pre-existent  life. 

Torula. — The  "  yeast-plant "  fungus. 

Vernier. — A  short  graduated  scale,  made  to  slide  along 
a  large  scale  so  as  to  read  to  fractions  of  divisions. 

Vibriones. — Vibratile  filaments,  or  bacteria,  sometimes 
moniliform,  or  bead-like,  frequently  found  in  decaying 
animal  infusions. 

Wandering  Cells. — Leucocytes,  or  'white  blood-cells, 
which  pass  through  the  coats  of  vessels  and  thence  into 
neighboring  tissues. 


INDEX. 


Aberration  of  lenses,  22 

Abiogenesis,  125 

Absorption  bands,  18,  101 

Acalephs,  166 

Acari,  177 

Achromatic  condenser,  33 

Acinetse,  162 

Accessories,  microsopic,  32 

Adjustment,  51 

Agriculture,  microscope  in,  18 

Air-pump,  79 

Alternation  of  generations,  126 

Algse,  139,  153 

Albumen  in  urine,  237 

Alimentary  canal  in  insects,  177 

Amici's  prism,  34 

Amoeba,  121 

Amoeboid  motion,  121 

Amplifier,  26 

Amyloid  infiltration,  229 

Amphlipleura  pellucida,  56 

Analysis  of  urine,  235 

of  earths,  etc.,  99,  108 
Anatomy  of  insects,  177 
Animal  histology,  182 
Animalcule  cage,  41 
Angular  aperture,  25,  55 

measurement  of  crystals,  89 
Annular  vessels,  131 
Annulata,  172 
Antennae  of  insects,  175 
Antiquity  of  microscope,  17 
Aquaria,  82 
Arachnida,  179 
Aristotle  on  life,  116 
Archeus,  116 


Bacteria,  135 
Bathybius,  96,  158 
Beale's  generalization,  118 

tint-glass  camera,  40 
Beck's  microscope,  32 

iris  diaphragm,  33 

illuminator,  38 
Biology,  microscope  in,  116 


Binocular  microscope,  30 
Bioplasm,  118 

varieties  of,  123 
Blood,  186 
Blood-tests,  102 
Blastema.  124 
Bone,  195 

Brunonian  movement,  53,  120 
Bryozoa,  168 
Bull's-eye  condenser,  36 


Cabinet,  81 

Carmine  staining,  69 

Care  of  microscope,  48 
of  the  eyes,  49 

Calcification,  229 

Camera  lucida,  39 

Camphor,  133 

Cancer,  234 

Capillary  structure,  201 

Cavities  in  crystals,  89 

Cell,  117 

formation  of,  119 
phenomena  of,  120 
movements  of,  120 
chemistry  of,  122 
forms  of,  123 
genesis,  124 
multiplication,  125 
wall,  vegetable,  129 

Cellulose,  129 

Cements,  75 

Cephalopoda.  171 

Cerebro-spinal  nerves,  216 

Characeas,  154 

Chalk  strata,  95 

Chemical  isolation,  59 
reagents,  67 
products,  183 

Chlorophyll,  133 

Chromatic  aberration,  22 

Chyle,  190 

Cilia,  124 

Cirrhipeds,  174 

Classes  of  microscopes,  28 


256 


INDEX. 


Ciliary  motion,  161,  170 
Chloride  of  sodium.  241 
Coal,  to  prepare,  92 
Colors  of  flowers,  133 
Collecting  objects,  81 
Coddington  lens,  23 
Colloid,  66 

degeneration,  231 
Compound  microscope,  23 

crystals,  89 

tissues,  197 
Collins's  Harley  microscope,  32 

graduating  diaphragm,  32 
C.ompressorium,  41 
Condensers,  33 
Condensing  lens,  37 
Connective  tissues,  192 
Conchifera,  170 
Correlation  of  force,  117 
Corti's  organ,  223 
Crystalline  forms,  86,  114 
Crystallization  of  salts,  100 
Crystalloid,  66 
Cryptogauaia,  152 
Crustacea,  172 
Cyclosis,  129 
Cystine,  241 


Dammar  mounting,  79 
Darker's  selenite  stage,  44 
Dark-ground  illumination,  35 
Decomposition  of  blood,  227 
Definition,  54 
Degeneration,  fatty,  230 
Dentine,  196 
Desmidiaceae,  140 
Development  of  tissues,  201 

of  fungi,  137 
Diabetic  sugar,  237 
Diaphragm,  32 
Diatom  markings,  56 
Diatoms,  94,  141 

classification  of,  142 
Diatomaceous  earth,  94 
Diffraction  of  light,  54 
Discrimination  of  forms,  127 
Dotted  ducts,  131 
Double  refraction,  91 
Dry  mounting,  78 
Dujardin,  118 


Early  microscopists,  20 
Echinoderms,  167 
Educational  microscopes,  30 
Epithelium,  190 

Elementary  unit  in  biology,  117 
Epiphytes,  242 
Epizoa,  243 
Equisetacese,  155 
Equisetum,  132 


Embryo,  sections  of,  205 

Embryonic  development,  201 

Entoiuostr;ica,  173 

Entozoa,  171,  243 

Enamel,  192 

Eozoon,  84,  97 

Errors  of  interpretation,  52 

from  refraction,  etc.,  52 
Examination,  methods  of,  58 

of  minerals,  85 

of  higher  plants,  155 
Eyes,  care  of,  49 

of  insects,  176 
Eye-pieces,  26 


Fatty  tissue.  195 

degeneration,  230 
Feet  of  insects,  177 
Ferns,  155 
Fission  of  cells,  125 
Fixed  oil  in  plants,  133 
Flatness  of  field,  55 
Fluid  media,  66 

mounting,  80 

cavities  in  minerals,  89 
Flowers,  157 
Focal  distance,  22 
Formed  material,  118,  128 
Forms  of  vegetable  cells.  134 
Formations,  pathological,  232 
Foraminifera,  95,  159 
Fossil  plants,  93 
Fraunhofer's  lines,  44.  101 
Frog-plate,  41 
Fungi,  134,  138 


Gas  chamber,  42 
Gasteropoda,  170 
Gemmation,  125 
Generative  organs,  213 
Germ-cell,  125 
Germinal  matter,  118,  122 
Geology,  microscope  in,  92 
Glass-covers,  77 
Glandular  fibres,  131 

tissues,  200 

Graduating  diaphragm,  33 
Grammatophora  test,  57 
Gum,  134 


Hair,  191 

of  insects,  175 
Haller,  118 
Hardening  tissues,  61 
Heart,  208 
Hepatica,  154 
Herapathite,  113 
Herschel's  doublet,  22 
High  powers,  55 


INDEX. 


257 


Hipparchia  Janira,  56 
Histo-chemi?try,  185 
Histology,  182 
Histologists,  early,  20 
Histological  structures,  185 
Holothuriee,  168 
Hunt,  Dr.,  on  staining,  153 
Hydrozoa,  165 


Imbedding  tissues,  62 
Immersion  lenses,  25,  51 
Indifferent  fluids,  66 
Infiltration,  228 
Infusoria,  160 

families  of,  163 
Injecting.  64 

syringe,  64 

material,  65,  70 
Insects,  174 

scales  of,  175 

hairs  of,  175 

eyes  of,  1 76 

mouths  of.  176 

feet  of,  177 

anatomy  of,  177 

changes  of.  126 
Intestinal  canal,  206 
Interpretation,  errors  of,  52 
Inverted  microscope,  106 
In  vertebra ta,  classes  of,  180 
lod-seruin,  66 
Iris  diaphragm,  33 


Kellners  eye-piece,  26 
Kidney,  211 


Labyrinthodon,  97 

Laticiferous  vessels,  131 

Lamps,  50 

Leaves  of  plants,  157 

Lasso-cells,  165 

Lenses,  21 

Lernoea,  173 

Leptothrix,  136 

Leucocytes,  189 

Lieberkuhn,  37 

Light  for  microscopes,  50 

Life,  theories  of,  116 

Litmus-paper,  107 

Living  bodies,  element  of,  117 

Ligneous  tissue,  130 

Lichens,  154 

Liver,  210 

Locomotive  organs,  215 

Low  powers,  55 

Lymph,  189 

Lymphatics,  207 

Luteine  spectra,  105 


Magnifying  power,  22 

Max  Schultze,  118 

Measuring  objects,  38 

Medium  powers,  55 

Metric  system,   39 

Medicine,  microscope  in,  226 

Metamorphosis,  126 

Microscope,  compound,  23 
mechanism  of,  27 

f      in  the  arts,  17 
in  commerce,  18 
in  agriculture,  18 
Micro-spectroscope,  44 
Micro-mineralogy,  84 
Micro -chemistry,  98 
Micro-chemical  analysis,  106 
Microscopic  slides,  77 
Microzymes,  135 
Milky  juice  in  plants,  131 
Mildew,  136 
Minute  lenses,  21 
dissection,  59 
Micro-gonidia,  152 
Micrometer,  38 
Moist-chamber,  41 
Moller's  test-plate,  57 
Mounting  objects,  76 
Molecular  movements,  120 

coalescence,  138 
M  on  era,  158 
Mosses,  154 
Morbid  actions,  227 
Morphological  products,  183 
Motile  cells,  120 
Mounting  in  balsam,  79 
Mucus,  190 
Mucoid  softening,  231 
Vluller's  eye-fluid,  68 
Vluscardine,  136 
Muscle,  197 
Mycelia  of  fungi,  137 


Cachet's  inverted  microscope,  32 

prism,  35 

tfavicula  rhomboides,  56 
Nerve  tissue,  198 

cells,  199 

preparations,  217 
'fichol's  prism,  43 
STobert's  illuminator,  35 

test,  56 
^ose-piece,  47 
^ostochinse,  151 
'fucleus  of  cells,  119 
utritive  organs,  206 

berhauser's  drawing  apparatus,  39 
bjects  of  microscopy,  58 
bject  glasses,  25 
finders,  48 


17 


258 


INDEX. 


Oblique  illumination,  34 
Ocular  micrometer,  38 
Opaque  injections,  65 

objects,  77 
Opticians,  list  of,  27 
Orbitolites,  159 
'Organs  of  touch,  218 

of  taste,  218 

of  smell,  218 

of  sight,  219 

•of  bearing,  222 
Origin  of  rocks,  92 
Organic  principles,  184 
Oolites,  90 
Otoliths,  222 
Oscillatoriae,  151 
Oxalate  of  lime,  241 


Pabulum,  118,  183 
Paleontology,  97 
Palmellaceffi,  139 
Parasites,  human,  242 
Parthenogenesis,   126 
Pathology,  microscope  in,  226 
Pathological  formations,  232 
Parabolic  illuminator,  36 

speculum,  37 
Pettenkofer's  test,  102 
Penetration.  55 
Periscopic  eye-piece,  26 
Preserving  objects,  76 
Pleurosigma  test,  58 
Pigott's,  Dr.  R..  eye-piece,  26 
Pigmentation,  229 
Phosphates,  240 
Physical  movements,  53 
Photography,  microscopic,  48 
Phenomena  of  cells,  120 
Polariscope,  42,  99 

in  mineralogy,  90 
Polycystina,  95,  160 
Polymorphism,  136 
Polyps,  164 
Polyzoa,  168 
Popular  microscopes,  30 
Porifera,  160 
Preparation,  58 

by  teasing,  61 

by  section,  61 

of  minerals.  84 

of  crystals/85,  99 

in  viscid  media,  65 

of  vegetables,  156 

embryonic,  204 
Preservative  fluids,  73 
Preserving  objects,  76 
Primordial  utricle,  129 
Protoplasm,  118 
Progressive  force,  130 
Prothallium  of  ferns,  126 
Prism  for  oblique  light,  35 


Protophytes,  129 
Protozoa,  158 
Pus,  189 


Raphides,  132 

Reade's  condenser,  34 

Recklinghausen's  moist-chamber,  41 

Red  blood-corpuscles,  186 

Reproduction,  125 

Resolution,  55 

Resin,  133 

Reticulated  vessels,  131 

Respiratory  organs,  213 

Retina,  221 

Rhodospermeae,  153 

Rhizopods,  158 

Rotatoria,  163 


Sarcode,  118 
Salivary  glands,  209 

corpuscles,  189 
Schleiden  and  Schwann,  118 
Sclerogen,  130 
Schultze's  warm  stage,  42 
Scales  of  Lepidoptera,  175 
Section-cutter,  63 
Secretory  organs,  208 
Sections  of  hard  tissues,  62 
Sensory  organs,  218 
Selenite  stage,  44 
Seeds,  157 

Shadbolt's  turntable,  78 
Shell  structure,  170 
Silica  in  plants,  131 
Simple  tissues,  186 
Soemmering's  steel  disk,  40 
Spectra  of  substances,  102 
Sperm-cell,  125 
Spectrum  analysis,  101 
Spiral  movements,  130 

vessels,  131 
Spot  lens,  36 
Sphagnum.  155 
Spherical  aberration,  22 
Sphaeroplea,  152 
Sponges,  160 

Spontaneous  generation,  125 
Stage  micrometer,  38 
Staining  cells,  122 

tissues,  63 

fluids,  69 
Starch,  132 
Stems  of  plants,  156 
Still  cells,  140 
Students'  microscopes,  28 
Strieker's  gas  chamber,  41 
Sublimation,  99 
Surirella  gemma,  56 
Stomata,  157 
Sputa,  243 


INDEX. 


259 


Sweat  glands,  209  , 

Sympathetic  nerve,  215 


Table,  50 
Tapeworm,  171 
Tactile  papillae,  218 
Tests,  microscopic,  54 

micro-chemical,  106 

for  alkalies,  108 

for  acids,  109 

for  oxides,  110 

for  blood,  102 

Theology  and  the  microscope,   19 
Thin  cells,  77 
Tissue  elements,  185 
Torula,  135 
Tow  net,  82 
Transformations,  126 
Transparent  injections,  72 
Triple  phosphates,  240 
Tumors,  232 
Turntable,  78 
Tunicata,  169 


Uric  acid,  240 
Urinary  deposits,  238 
Ulvacese,  151 


Varieties  of  bioplasm,  123 
Vascular  tissue,  201 
Valentine's  knife,  62 
Vernier,  43 
Vegetable  cells,  128 
Vibriones,  135 
Vinegar  eels,  171 
Vorticella,  161 
Volatile  oil,  133 
Volvox,  140 


Warm  stage,  42 
Wandering  cells,  121 
Water  bears,  164 

fleas,  173 

Wenham's  prism,  30 
Webster  condenser,  34 
White  blood-cells,  188 
Wollaston's  doublet,  23 


Xanthidia, 


Zentmayer's  microscope,  30 
Zoology,  microscope  in,  158 
Zoophytes,  164 
Zygnema,  151 


DIRECTIONS    FOR    THE    PLATES. 


Plate 


1 

to  face  page     56. 

Plate  15  to 

face  page  168. 

2 

11               92. 

"      16 

"            170. 

3 

"             112. 

cc      17 

"            176. 

4 

"             114. 

"      18 

"            188. 

5 

"             120. 

«      19 

"            192. 

6 

"             130. 

"      20 

"             196. 

7 

"             132. 

"      21 

"            200. 

8 

"             134. 

"      22 

"            208. 

9 

"             136. 

"      23 

««            210. 

10 

140. 

"      24 

"            222. 

11 

"             154. 

»      25 

»            234. 

12 

«             160. 

"      26 

"            238. 

13 

"             167. 

"      27 

«            240. 

14 

"             166. 

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a  work  of  reference. 

ALLINGHAM  (WILLIAM),  F.  R.  C.  S., 

Surgeon  to  St,  Mark's  Hospital  for  Fistula,  &c, 

FISTULA,  HEMORRHOIDS,  PAINFUL  ULCER,  STRICT- 
URE, PROLAPSUS,  and  other  Diseases  of  the  Rectum,  their  Diagnosis 
and  Treatment.  Second  Edition,  Revised  and  Enlarged  by  the 
Author.  Price  .  .  .  .  .  .  .  .  $2.00 

This  book  has  been  well  received  by  the  Profession ;  the  first  edition  sold  rap  * 
idly ;  the  present  one  has  been  revised  by  the  author,  and  some  additions  made, 
chiefly  as  to  the  mode  of  treatment. 

The  Medical  Press  and  Circular,  speaking  of  it,  says :  "  No  book  on  this  special  subject 
can  at  all  approach  Mr.  Allingham's  in  precision,  clearness,  and  practical  good  sense." 

The  London  Lancet :  "  As  a  practical  guide  to  the  treatment  of  affections  of  the  lower 
bowel,  this  book  is  worthy  of  allcommendafion." 

The  Edinburgh  Monthly :  "  We  cordially  recommend  it  as  well  deserving  the  careful  study 
of  Physicians  and  Surgeons." 


6 

ATTHILL  (LOMBE),  M.  D., 

Fellow  and  Examiner  in  Midwifery,  Kmg  and  Queen's  College  of  Physicians,  Dublin. 

CLINICAL  LECTURES  ON  DISEASES  PECULIAR  TO  WO- 
MEN. Second  Edition,  Revised  and  Enlarged,  with  Six  Lithographic 
Plates  and  other  Illustrations  on  Wood.  Price  .  .  .  ^2.2^ 

The  value  and  popularity  of  this  book  is  proved  by  the  rapid  sale  of  the  first  edition, 
which  was  exhausted  iu  h-ss  tluui  a  year  from  the  tune  of  its  publication.  It  appears  t<? 
possess  three  great  merits  :  First,  It  treats  of  the  diseases  very  common  to  females.  Second, 
It  treats  of  them  in  a  thoroughly  clinical  and  practical  manner.  Third,  It  is  concise,  orig- 
inal, and  illustrated  by  numerous  ca>e-  frm  the  author's  own  experience.  His  style  is  clear 
and  the  volume  is  the  result  of  the  author's  large  and  accurate  clinical  observation  recorded 
in  a  remarkable,  perspicuous,  and  terse  manner,  and  is  conspicuous  for  the  best  qualities  of 
a  practical  guide  to  the  student  and  practitioner.  — JBritith  Medical  Journal. 

ADAMS  (WILLIAM),  F.  R.  C.  S., 

Surgeon  to  the  Royal  Orthopedic  and  Great  Northern  Hospitals, 

CLUB-FOOT:  ITS  CAUSES,  PATHOLOGY,  AND  TREAT- 
MENT. Being  the  Jacksonian  Prize  Essay  of  the  Royal  College  of 
Surgeons.  A  New  Revised  and  Enlarged  Edition,  with  106  Illustrations 
engraved  on  Wood,  and  Six  Lithographic  Plates.  A  large  Octavo 
Volume.  Price $6.00 


ADAMS  (ROBERT),  M.  D., 

Regius  Professor  of  Surgery  in  the  University  of  Dublin,  &c.,  &d 

RHEUMATIC  GOUT,  OR  CHRONIC  RHEUMATIC  ARTHRI- 
TIS OF  ALL  THE  JOINTS.  The  Second  Edition.  Illustrated  by 
numerous  Woodcuts,  and  a  quarto  Atlas  of  Plates.  2  Volumes. 
Price  .  .  .  '  .  ' $8.50 

ALTHAUS  (JULIUS),  M.D., 

Physician  to  the  Infirmary  of  Epilepsy  and  Paralysis, 

A  TREATISE  ON  MEDICAL  ELECTRICITY,  Theoretical  and 
Practical,  and  its  Use  in  the  Treatment  of  Paralysis,  Neuralgia,  and  other 
Diseases.  Third  Edition,  Enlarged  and  Revised,  with  One  Hundred 
and  Forty-six  Illustrations.  In  one  volume  octavo.  Price  .  $6.00 

In  this  work  both  the  scientific  and  practical  aspects  of  the  subject  are  ably,  concisely,  and 
thoroughly  treated.  It  is  much  the  best  work  treating  of  the  remedial  effects  of  electricity 
in  the  English  language.  —  New  York  Medical  Record. 

ARNOTT  (HENRY),  F.R.C.S. 

CANCER:  its  Varieties,  their  Histology  and  Diagnosis.  With  Five 
Lithographic  Plates  and  Twenty-two  Wood  Engravings.  Price  $2.25 

AGNEW  (D.  HAYES),  M.D., 

Professor  of  Surgery  in  the  University  of  Pennsylvania. 

THE  LACERATIONS  OF  THE  FEMALE  PERINEUM,  AND 
VESICO-VAGINAL  FISTULA,  their  History  and  Treatment,  with 
numerous  Illustrations.  Octavo.  Price  .  .  .  $2.00 

Prof.  Agnew  has  been  a  most  indefatigable  laborer  in  this  department,  and  his  work  stands 
deservedly  high  in  the  estimation  of  the  profession.  It  is  well  illustrated,  and  full  descrip- 
tions of  the  operations  and  instruments  employed  are  given.  —  Canada  Lancet. 


ACTON  (WILLIAM),  M.R.C.S.,  ETC. 

THE  FUNCTIONS  AND  DISORDERS  OF  THE  REPRODUC- 
TIVE ORGANS.  In  Childhood,  Youth,  Adult  Age,  and  Advanced 
Life,  considered  in  their  Physiological,  Social,  and  Moral  Relations, 
Fourth  American  from  the  Fifth  London  Edition.  Carefully  revised  by 
the  Author,  with  additions.  .  ,  ,  .  .  .  .  $3.00 

Mr.  Acton  lias  done  good  service  to  society  by  grappling  manfully  with  sexual  vice,  and 
we  trust  that  others,  whose  position  as  men  of  science  and  teachers  enable  them  to  sjx-sik 
with  authority,  will  assist  in  combating  and  arresting  the  evils  which  it  entails.  The  spirit 
which  pervadesJiis  book  is  one  which  does  credit  equally  to  the  head  and  to  the  heart  of  the 
author.  —  British  and  Foreign  Medico- Cliirurgical  Review, 

SAME  AUTHOR. 

PROSTITUTION:  Considered  in  its  Moral,  Social,  and  Sanitary  As- 
pects. Second  Edition,  Enlarged.  Price  .  ,  ,  .  $5.00 

ANSTIE  (FRANCIS  E.),  M.D., 

Lecturer  on  Materia  Medica  and  Therapeutics,  etc. 

STIMULANTS  AND  NARCOTICS.  Their  Mutual  Relations,  with 
Special  Researches  on  the  Action  of  Alcohol,  Ether,  and  Chloroform 
on  the  Vital  Organism.  Octavo.  .  $3-00 

ANDERSON   (M  CALL),  M.D.,. 

Professor  of  Clinical  Medicine  in  the  University  of  Glasgow,  &c, 

ECZEMA.  The  Pathology  and  Treatment  of  the  various  Eczema- 
tous  Affections  or  Eruptions  of  the  Skin.  The  Third  Revised  and  En- 
larged Edition.  Octavo.  Price $2.75 

BUZZARD  (THOMAS),  M.  D., 

Physician  to  the  National  Hospital  for  Paralysis  and  Epilepsy, 

CLINICAL  ASPECTS  OF   SYPHILITIC    NERVOUS  AFFEC- 
TIONS.     121110.     Cloth.     Price $1.75 

BASH  AM  (w.  R.),  M.D.,  F.R.C.P., 

Senior  Physician  to  the  Westminster  Hospital,  &c. 

AIDS  TO  THE  DIAGNOSIS  OF  DISEASES  OF  THE  KID- 
NEYS. With  Ten  large  Plates.  Sixty  Illustrations.  Price  .  $2.00 

SAME  AUTHOR. 

ON  DROPSY,  AND  ITS  CONNECTION  WITH  DISEASES  OF 
THE  KIDNEYS,  HEART,  LUNGS  AND  LIVER.  With  Sixteen 
Plates.  Third  Edition.  Octavo.  .  -.  .  .  .  $5.00 

M.  BARTH  AND  M.  HENRI  ROGER. 

A  MANUAL  OF  AUSCULTATION  AND  PERCUSSION.  A 
new  Translation,  from  the  Sixth  French  Edition.  .  .  .  $1.25 

S.  M.  BRADLEY,  JF.  R.  C.  S. 

Senior  Assistant  Surgeon  Manchester  Royal  Infirmary, 

A  MANUAL  OF  COMPARATIVE  ANATOMY  AND  PHYSI- 
OLOGY. With  60  Illustrations.  Third  Edition.  Price  .  $2.50 


BEALE  (LIONEL  s.),  M.D. 

DISEASE  GERMS:  AND  ON  THE  TREATMENT  OF  DIS- 
EASES CAUSED  BY  THEM. 

PART      I.— SUPPOSED  NATURE  OF  DISEASE  GERMS. 
PART    II.  — REAL  NATURE  OF  DISEASE  GERMS. 
PART  III.  — THE  DESTRUCTION  OF  DISEASE  GERMS. 

Second  Edition,  much  enlarged,  with  Twenty-eight  full-page  Plates, 
containing  117  Illustrations,  many  of  them  colored.  Demy  Octavo. 

Price $5-°° 

This  new  edition,  besides  including  the  contents  revised  and  enlarged  of  the  two  former 

editions  published  by  Dr.  Beale  on  Disease  Germs,  has  an  entirely  new  part  added  on  "  The 

Destruction  of  Disease  Germs." 

SAME  AUTHOR. 

BIOPLASM.  A  Contributiori  to  the  Physiology  of  Life,  or  an  Intro- 
duction to  the  Study  of  Physiology  and  Medicine,  for  Students.  With 
Numerous  Illustrations.  Price  .  .  .  .  .  $3-°° 

This  volume  is  intended  as  a  TEXT-BOOK  for  Students  of  Physiology,  explaining  the  nature 
of  some  of  the  most  important  changes  which  are  characteristic  of  and  peculiar  to  living 
beings. 

PROTOPLASM,  OR  MATTER  AND  LIFE.  Third  Edition,  very 
much  Enlarged.  Nearly  350  pages.  Sixteen  Colored  Plates.  One 
volume.  Price $4-5° 

PART  I.  DISSENTIENT.      PART  II.  DEMONSTRATIVE.     PART  III.  SUGGESTIVE. 

HOW  TO  WORK  WITH  THE  MICROSCOPE.  Fourth  Edition, 
containing  400  Illustrations,  many  of  them  colored.  Octavo.  Price 

This  work  is  a  complete  manual  of  microscopical  manipulation,  and  contains  a  full  descrip- 
tion of  many  new  processes  of  investigation,  with  directions  for  examining  objects  under  the 
highest  powers,  and  for  taking  photographs  of  microscopic  objects. 

ON  KIDNEY  DISEASES,  URINARY  DEPOSITS,  AND  CAL- 
CULOUS  DISORDERS.  Including  the  Symptoms,  Diagnosis,  and 
Treatment  of  Urinary  Diseases.  With  full  Directions  for  the  Chemical 
and  Microscopical  Analysis  of  the  Urine  in  Health  and  Disease.  The 
Third  Edition.  Seventy  Plates,  415  figures,  copied  from  Nature. 
Octavo.  Price  .  .  .  .  .  .  .  •  .  .  $10.00 

THE  USE  OF  THE  MICROSCOPE  IN  PRACTICAL  MEDI- 
CINE. For  Students  and  Practitioners,  with  full  directions  for  exam- 
ining the  various  secretions,  &c.,  in  the  Microscope.  Fourth  Edition. 
500  Illustrations.  Octavo.  Preparing. 

BLOXAM  (c.  L.), 

Professor  of  Chemistry  in  King's  College,  London, 

CHEMISTRY,  INORGANIC  AND  ORGANIC.  With  Experi- 
ments and  a  Comparison  of  Equivalent  and  Molecular  Formulae.  With 
276  Engravings  on  Wood.  Second  Edition,  carefully  revised.  Octavo. 
Price,  in  cloth,  $4.00;  leather,  - $5.00 

SAME  AUTHOR. 

LABORATORY  TEACHING;  OR  PROGRESSIVE  EXER- 
CISES IN  PRACTICAL  CHEMISTRY.  Third  Edition.  With 
Eighty-nine  Engravings.  Crown  Octavo.  Price  .  .  .  $2.00 


9 
BENNETT  (J.HENRY),  M.  D. 

NUTRITION  IN  HEALTH  AND  DISEASE.  A  Contribution  to 
Hygiene  and  to  Clinical  Medicine.  Second  Edition,  Revised  and  En- 
larged. Octavo.  Cloth.  Price  .  .  .  .  .  .  $2.50. 

BIRCH  (s.  B.),  M.D., 

Member  cf  t!ie  Royal  College  of  Physicians,  &c. 

CONSTIPATED  BOWELS ;  the  Various  Causes  and  the  Different 
Means  of  Cure.  Third  Edition.  Price  .  .  .  $1.00 

BUCKNILL  (JOHN  CHARLES),  M.D.,  &  TUKE  (DANIEL  H.),  M.D. 

A  MANUAL  OF  PSYCHOLOGICAL  MEDICINE:  containing  the 

Lunacy  Laws,  the  Nosology,  CEtiology,  Statistics,  Description,  Diagno- 
•   sis,  Pathology  (including  Morbid  Histology),  and  Treatment  of  Insanity. 
Third  Edition,  much  enlarged,  with   Ten  Lithographic  Plates,  and  nu- 
merous other  Illustrations.     Octavo.      Price     ....     $8.00 

This  edition  contains  upwards  of  200  pages  of  additional  matter,  and,  in  consequence  of 
recent  advances  in  Psychological  Medicine,  several  ^chapters  have  been  rewritten,  bringing 
the  Classification,  Pathology,  and  Treatment  of  Insanity  up  to  the  present  time. 

BROWNE  (j.  H.  BALFOUR),  ESQ. 

MEDICAL  JURISPRUDENCE  OF  INSANITY.  Second  Edition, 
very  much  Enlarged.  With  References  to  the  Scotch  and  American 
Decisions,  etc.,  etc.  Octavo.  Price  .....  $5.00 

BIDDLE  ^JOHN~B.),  M.  D., 

Professor  of  Materia  Medica  and  Therapeutics  in  the  Jefferson  Medical  College,  Philadelphia,  &c, 

MATERIA  MEDICA,  FOR  THE  USE  OF  STUDENTS.  With 
Illustrations.  Seventh  Edition,  Revised  and  Enlarged.  Price  $4.00 

This  new  and  thoroughly  revised  edition  of  Professor  Biddle's  work  has  incorporated  in 
it  all  the  improvements  as  adopted  by  the  New  United  States  Pharmacopoeia  just  issued.  It 
is  designed  to  present  the  leading  facts  and  principles  usually  comprised  under  this  head  as 
set  forth  by  the  standard  authorities,  and  to  fill  a  vacuum  which  seems  to  exist  in  the  want 
of  an  elementary  work  on  the  subject.  The  larger  works  usually  recommended  as  text-books 
in  our  Medical  schools  are  too  voluminous  for  convenient  use.  This  will  be  found  to  contain, 
in  a  condensed  form,  all  that  is  "most  valuable,  and  will  supply  students  with  a  reliable  guide 
to  the  course  of  lectures  on  Materia  Medica  as  delivered  at  the  various  Medical  schools  in 
the  United  States.  __ 

BALFOURToTw.),  M.  D., 

Physician  to  the  Royal  Infirmary,  Edinburgh;  Lecturer  on  Clinical  Medicine,  &c, 

CLINICAL  LECTURES  ON  DISEASES  OF  THE  HEART  AND  , 
AORTA.     With  Illustrations.     Octavo.     Price       .         .         .     $5.00 

BYFORD  (wTn!),  A.M.,  M.D., 

Professor  of  Obstetrics  and  Diseases  of  Women  and  Children  in  the  Chicago  Medical  College,  &c, 

PRACTICE. OF  MEDICINE  AND  SURGERY.  Applied  to  the 
Diseases  and  Accidents  incident  to  Women.  Second  Edition,  Revised 
and  Enlarged.  Octavo.  Price,  cloth,  $5.00;  sheep  .  .  $6.00 

SAME  AUTHOR. 

ON  THE  CHRONIC  INFLAMMATION  AND  DISPLACEMENT 
OF  THE  UNIMPREGNATED  UTERUS.     A  New,  Enlarged,  and 
Thoroughly  Revised  Edition,  with  Numerous  Illustrations.   Octavo.   $3 
Dr.  Byford  writes  the  exact  present  state  of  medical  knowledge  on  the  subjects  presented ;  . 
and  does  this  so  clearly,  so  concisely,  so  truthfully,  and  so  completely,  that  his  book  on  the 
uterus  will  always  meet  the  approval  of  the  profession,  and  be  everywhere  regarded  as  a 
popular  standard  work.  —  Buffalo  Medical  and  Surgical  Journal. 


10 
BLACK   (D.  CAMPBELL),  M.  D., 

L  R,  C,  S.  Edinburgh,  Member  of  the  General  Council  of  the  University  of  Glasgow,  &c.,  &c, 

THE  FUNCTIONAL  DISEASES  OF  THE  RENAL,  URINARY, 

and  Reproductive  Organs,  with  a  General  View  of  Urinary  Pathology. 
Price $2.50 

The  style  of  the  author  is  clear,  easy,  and  agreeable,  .  .  .  his  work  is  a  valuable  contri- 
bution to  medical  science,  and  being  penned  in  that  disposition  of  unprejudiced  philosophical 
inquiry  which  should  always  truide  a  true  physician,  admirably  embodies  the  spirit  of  its 
opening  quotation  from  Professor  Huxley.  —  Philada.  Med.  Tillies. 

BY  SAME  AUTHOR. 

LECTURES   ON   BRIGHT'S    DISEASE  OF  THE   KIDNEYS. 

Delivered  at  the  Royal  Infirmary  of  Glasgow.     With  20  Illustrations, 
engraved  on  Wood.     One  volume,  octavo,  in  Cloth.     Price     .     $2.00 

BENTLEY  AND  TRIMEN'S 

MEDICINAL  PLANTS.  A  New  Illustrated  Work,  now  Publish- 
ing in  Monthly  Parts.  Thirteen  Parts  now  ready.  Eight  Colored 
Plates  in  each  Part.  Price,  each,  .  ....  .  .  $2.00 

This  work  includes  full  botanical  descriptions,  and  an  account  of  the  properties  and  uses 
of  the  principal  plants  employed  in  medicine,  especial  attention  being  paid  to  those  which 
are  officinal  in  the  British  and  United  States  Pharmacopoeias.  The  plants  which  supply 
food  and  substances  required  by  the  sick  and  convalescent  will  be  also  included.  Each  spe- 
cies will  be  illustrated  by  a  colored  plate  drawn  from  nature. 

BEASLEY  (HENRY). 

THE  BOOK  OF  PRESCRIPTIONS.  Containing  over  3000 
Prescriptions,  collected  from  the  Practice  of  the  most  Eminent  Physi- 
cians and  Surgeons  —  English,  French,  and  American;  comprising  also 
a  Compendious  History  of  the  Materia  Medica,  Lists  of  the  Doses  of  all 
Officinal  and  Established  Preparations,  and  an  Index  of  Diseases  and 
their  Remedies.  Fifth  Edition,  Revised  and  Enlarged.  Price  $2.50 

BY  SAME  AUTHOR. 

THE  POCKET  FORMULARY:  A  Synopsis  of  the  British  and 
Foreign  Pharmacopoeias.  Ninth  Revised  Edition.  Price  .  $2.50 

THE  DRUGGIST'S  GENERAL  RECEIPT  BOOK  AND  VETERI- 
NARY FORMULARY.  Seventh  Edition.  Price.  $2.50 

BRANSTON   (THOMAS  r.). 

HAND-BOOK  OF  PRACTICAL  RECEIPTS.  For  the  Chemist, 
Druggist,  &c. ;  with  a  Glossary  of  Medical  and  Chemical  Terms.  $1.50 

BRAUNE— BELLAMY. 

AN  ATLAS  OF  TOPOGRAPHICAL  ANATOMY.  After  Plane 
Sections  of  Frozen  Bodies,  containing  Thirty-four  Full-page  Photo- 
graphic Plates  and  numerous  other  Illustrations  on  Wood.  By  WILHKLM 
BRAUNE,  Professor  of  Anatomy  in  the  University  of  Leipzig.  Trans- 
lated and  Edited  by  EDWARD  BELLAMY,  F.  R.  C.  S.,  Senior  Assistant  Sur- 
geon to,  and  Lecturer  on  Anatomy  and  Teacher  of  Operative  Surgery 
at,  the  Charing  Cross  Hospital,  London.  A  large  quarto  volume. 
Price  in  cloth,  $12.00  ;  half  morocco,  .....  $14.00 


11 

COHEN   (i.  SOLIS),  M.D. 

Lecturer  on  Laryngoscopy  and  Diseases  of  the  Throat  and  Chest  in  Jefferson  Medical  College, 

ON  INHALATION.  ITS  THERAPEUTICS  AND  PRACTICE. 
Including  a  Description  of  the  Apparatus  employed,  &c.  With  Cases 
and  Illustrations.  A  New  Enlarged  Edition.  Price  .  .  $2.75 

SAME  AUTHOR. 

CROUP.     In  its  Relations  to  Tracheotomy.     Price         .         .    $1.00 

CARSON  (JOSEPH),  M.D., 

Professor  of  Materia  Medica  and  Pharmacy  in  the  University, 

A  HISTORY  OF  THE  MEDICAL  DEPARTMENT  OF  THE 
UNIVERSITY  OF  PENNSYLVANIA,  from  its  Foundation  in  1765: 

with  Sketches  of  Deceased  Professors,  &c $2.00 

The  history  of  the  University  of  Pennsylvania  has  a  national  as  well  as  a  local  interest, 
from  the  early  date  of  its  origination,  and  the  connection  with  it  of  men  of  illustrious  public 
reputation,  such  as  Drs.  Franklin,  Rush,  Physick,  Gibson,  Dewees,  C'hapnuin,  Wood,  &c.,  &c. 
For  the  labor  and  love  which  he  has  spent  in  preparing  this  most  interesting  and  valuable 
work,  Prof,  Carson  has  earned  the  gratitude  of  the  alumni  of  the  University,  and  of  all  others 
interested  in  medical  education  in  this  country.  —  American  Journal  of  Medical  Science. 

CARPENTER  (w.  B.),  M.D.,  F.R.S. 

THE  MICROSCOPE  AND  ITS  REVELATIONS.  The  Fifth 
London  Edition,  Revised  and  Enlarged,  with  more  than  500  Illustra- 
tions  $5-5° 

SAME  AUTHOR. 

PRINCIPLES  OF  HUMAN  PHYSIOLOGY.  The  Eighth  Revised 
and  Enlarged  Edition.  With  nearly  400  Illustrations  on  Steel  and 
Wood.  Edited  by  Mr.  HENRY  POWER.  1200  pages.  Octavo.  $5.50 

CHAVASSE  (P.  HENRY),  F.R.C.S., 

Author  of  Advice  to  a  Wife,  Advice  to  a  Mother,  &c. 

APHORISMS  .ON   THE    MENTAL   CULTURE  AND  TRAIN- 
ING OF  A  CHILD,  and  on  various  other  subjects  relating  to  Health 
and  Happiness.     Addressed  to  Parents.     Price         .         .         .     $1.50 
Dr.  Chavasse's  works  have  been  very  favorably  received  and  had  a  large  circulation,  the 
value  of  his  advice  to  WIVES  and  MOTHERS  having  thus  been  very  generally  recognized. 
This  book  is  a  sequel  or  companion  to  them,  and  itwill  be  found  both  valuable  and  important 
to  all  who  have  the  care  of  families,  and  who  want  to  bring  up  their  children  to  become  useful 
men  and  women.     It  is  full  of  fresh  thoughts  and  graceful  illustrations. 

CLARKE  (W.FAIRLIE),  M.D., 

Assistant  Surgeon  to  Charing  Cross  Hospital. 

CLARKE'S   TREATISE  ON  DISEASES   OF   THE   TONGUE. 

With  Lithographic  and  Wood-cut  Illustrations.     Octavo.     Price  $5.00 
It  contains 
ination, 
Syphilis  and 

COOPER  (s.). 

A  DICTIONARY  OF  PRACTICAL  SURGERY  AND  ENCY- 
CLOPAEDIA OF  SURGICAL  SCIENCE.  New  Edition,  brought 
down  to  the  present  time.  By  SAMUEL  A.  LANE,  F.R.C.S.,  assisted  by 
other  eminent  Surgeons.  In  two  vols.,  of  over  1000  pages  each.  $15.00 


12 
CLAY  (CHARLES),  M.  D. 

Fellow  of  the  London  Obstetrical  Society,  &c. 

THE  COMPLETE  HAND-BOOK  OF  OBSTETRIC  SURGERY, 
or,  Short  Rules  of  Practice  in  Every  Emergency,  from  the  Simplest  to 
the  most  Formidable  Operations  in  the  Practice  of  Surgery.  First 
American  from  the  Third  London  Edition.  With  numerous  Illustra- 
tions. In  one  volume.  $2.25 

CHAMBERS  (THOMAS  K.),  M.  D., 

LECTURES,  CHIEFLY  CLINICAL.  Illustrative  of  a  Restorative 
System  of  Medicine. 

CORMACK  (SIR  JOHN  jfosfc),  K.  B.,  F.  R.  S.  E.,  M.  D. 

Edinburgh  and  Paris,  Fellow  Royal  College  of  Physicians,  Physician  to  the  Hertford  British  Hospital,  Paris,  &c, 

CLINICAL  STUDIES,  Illustrated  by  Cases  observed  in  Hospital  and 
Private  Practice.  With  Illustrative  Plates.  2  Volumes.  Octavo.  $6.50 

COBBOLD  (T.  SPENCER),  M.D.,  F.R.S. 

WORMS:  a  Series  of  Lectures  delivered  at  the  Middlesex  Hospital 
on  Practical  Helminthology.  Post  Octavo.  .  •  .  .  $2.00 

CLEAVELAND  (c.  H.),  M.D., 

Member  of  the  American  Medical  Association,  &c. 

A  PRONOUNCING  MEDICAL  LEXICON.    Containing  the  Cor- 
rect Pronunciation  and  Definition  of  Terms  used  in  Medicine  and  the 
Collateral  Sciences.     Improved  Edition,  Cloth,  $1.25  ;  Tucks,      #1.50 
This  work  is  not  only  a  Lexicon  of  all  the  words  in  common  use  in  Medicine,  but  it  is 
also  a  Pronouncing  Dictionary,  a  feature  of  great  value  to  Medical  Students.     To  the  Dis- 
penser it  will  prove  an  excellent  aid,  and  also  to  the  Pharmaceutical  Student.    'It  has  received 
strong  commendation  both  from  the  Medical  Press  and  from  the  profession. 

COLES  (OAKLEY),  D.D.S. 

Dental  Surgeon  to  the  Hospital  for  Diseases  of  the  Throat,  &c, 

A  MANUAL  OF  DENTAL  MECHANICS.  Containing  much 
information  of  a  Practical  Nature  for  Practitioners  and  Students. 

INCLUDING 
The  Preparation  of  the  Mouth  for  Artificial  Teeth,  on  Taking  Impressions,  Various 


kjvi.  j  j   JL   J  ,111,     v^l  31  H£^    C»UVt    ±\  VAJ  UOIAII^    J.»A±11C1  t4JL     JLCCL1J.    LilC 

Vulcanite  Base,  the  Celluloid  Base,  Treatment  of  Deformities  of  the  Mouth,  Receipts 

for  Making  Gold  Plate  and  Solder,  etc.,  etc. 

With  140  Illustrations.     Price $2.50 

SAME  AUTHOR. 

ON  DEFORMITIES  OF  THE  MOUTH,  CONGENITAL  AND 

ACQUIRED,  with  their  Mechanical  Treatment.     Second  Edition,  Re- 

.  vised  and  Enlarged.     With  Illustrations.     Price,     .         .         .     $2.50 

CURLING  (T.B.),  F.R.S. 

Consulting  Surgeon  to  London  Hospital,  &c, 

OBSERVATIONS  ON  DISEASES  OF  THE  RECTUM.  With 
Illustrations.  Fourth  Edition,  Revised  and  Enlarged.  Octavo.  Cloth. 
Price $2.75 


13 
CLARK  (F.  LE  GROS),  F.  R.  S., 

Senior  Surgeon  to  St.  Thomas's  Hospital, 

OUTLINES  OF  SURGERY  AND  SURGICAL   PATHOLOGY, 

including  the  Diagnosis  and  Treatment  of  Obscure  and  Urgent  Cases, 
and  the  Surgical  Anatomy  of  some  Important  Structures  and  Regions. 
Assisted  by  W.  W.  WAGSTAFFE,  F.  R.  C.  S.,  Resident  Assistant-Surgeon 
of,  and  Joint  Lecturer  on  Anatomy  at,  St.  Thomas's  Hospital.  Second 
Edition,  Revised  and  Enlarged.  Price  ....  $3.00 

This  edition  brings  the  work  up  to  the  highest  level  of  our  present  knowledge,  incorporat- 
ing all  that  is  sound  and  recent  in  Physiology  so  far  as  it  relates  to  subjects  requiring  its 
aid.  It  is  not  alone  an  admirable  exposition  of  the  principles  of  Surgery,  but  a  trusty  guide 
to  the  emergencies  of  Practice.  We  cannot  too  highly  estimate  the  ability  to  condense  and 
the  results  of  a  ripened  experience  furnished  to  us  here  in  a  readable  and  practical  form.  — 
Med.  Times  and  Gazette. 

COOLEY  (A.  j.). 

CYCLOPAEDIA  OF  PRACTICAL  RECEIPTS.  Containing  Pro- 
cesses and  Collateral  Information  in  the  Arts,  Manufactures,  Profes- 
sions, and  Trades,  including  Medicine,  Pharmacy,  and  Domestic 
Economy ;  designed  as  a  General  Book  of  Reference  for  the  Manufac- 
turer, Tradesman,  Amateur,  and  Heads  of  Families.  The  Fifth  Edi- 
tion, Revised  and  partly  Rewritten  by  RICHARD  V.  TUSON,  F.C.S.,  &c. 
Over  1000  royal-octavo  pages,  double  columns.  With  Illustrations. 
Price $10.00 

Every  part  of  this  edition  has  been  subjected  to  a  thorough  and  complete  revision  by  the 
editor,  assisted  by  other  scientific  gentlemen.  In  the  chemical  portion  of  the  book,  every 
subject  of  practical  importance  has  been  retained,  corrected,  and  added  to;  to  the  name  of 
every  substance  of  established  composition  a  formula  has  been  attached ;  while  to  tlie  Phar- 
maceutist its  value  has  been  greatly  increased  by  the  additions  which  have  been  made  from 
the  British,  Indian,  and  United  States  Pharmacopoeias. 

CAZEAUX  (P.),  M.  D., 

Adjunct  Professor  of  the  Faculty  of  Medicine,  Paris,  et^. 

A  THEORETICAL  AND  PRACTICAL  TREATISE  ON  MIDWIFERY, 
including  the  Diseases  of  Pregnancy  and  Parturition.  Translated  from 
the  Seventh  French  Edition,  Revised,  Greatly  Enlarged,  and  Improved, 
by  S.  TARNIER,  Clinical  Chief  of  the  Lying-in  Hospital,  Paris,  etc., 
with  numerous  Lithographic  and  other  Illustrations.  Price,  in  Cloth, 
$6.50;  in  Leather,  $7.50. 

M.  Cazeaux's  Great  Work  on  Obstetrics  has  become  classical  in  its  character,  and  almost 
an  Encyclopaedia  in  its  fulness.  Written  expressly  for  the  use  of  students  of  medicine,  its 
teachings  are  plain  and  explicit,  presenting  a  condensed  summary  of  the  leading  principles 
established  by  the  masters  of  the  obstetric  art,  and  such  clear,  practical  directions  for  the 
management  of  the  pregnant,  parturient,  and  puerperal  states,  as  have  been  sanctioned  by 
the  most  authoritative  practitioners,  and  confirmed  by  the  author's  own  experience. 

DOBELL  (HORACE),  M.  D., ' 

Senior  Physician  to  the  Hospital, 

WINTER  COUGH  (CATARRH,  BRONCHITIS,  EMPHYSEMA, 

ASTHMA).  Lectures  Delivered  at  the  Royal  Hospital  for  Diseases  of  the 

.  Chest.     The  Third  Enlarged  Edition,  with  Colored  Plates.     Octavo. 

Price $3-5° 

This  work  has  been  thoroughly  revised.  Two  new  Lectures  have  been  added  —  viz., 
Lecture  IV.,  "On  the  Natural  Course  of  Neglected  Winter  Cough,  and  on  the  Interdepen- 
dence of  Winter  Cough  with  other  Diseases ;  "  Lecture  IX.,  "  On  Change  of  Climate  in  Winter 
Cough."  Also  additional  matter  on  Post-nasal  Catarrh,  Ear-Cough,  Artificial  Respiration  as 
a  means  of  Treatment,  Laryngoscopy,  New  Methods  and  Instruments  in  Treating  of 
eema,  a  good  Index,  and  Colored  Plates,  with  appended  Diagnostic  Physical  signs. 


14 
DIXON  (JAMES),  F.  R.  C.  S. 

Surgeon  to  the  Royal  London  Ophtha  mic  Hospital,  &c, 

A  GUIDE  TO  THE  PRACTICAL  STUDY  OF  DISEASES  OF 
THE  EYE,  with  an  Outline  of  their  Medical  and  Operative  Treatment, 
with  Test  Types  and  Illustrations.     Third  Edition,  thoroughly  Revised, 
and  a  great  portion  Rewritten.     Price     .         .         .         .        ..     £2.50 

Mr.  Dixon's  book  is  essentially  a  practical  one,  written  by  an  observant  author,  who  brings 

to  his  special  subject  asouud  knowledge  of  general  Medicine  and  Surgery. — Dublin  Quarterly. 

DILLNBERGER  (DR.  EMIL). 

A  HANDY-BOOK  OF  THE  TREATMENT  OF  WOMEN  AND 
CHILDREN'S  DISEASES,  according  to  the  Vienna  Medical  School. 
Part  I.  The  Diseases  of  Women.  Part  II.  The  Diseases  of  Children. 
Translated  from  the  Second  German  Edition,  by  P.  NICOL,  M.  D. 
Price .  .  $1.75 

Many  practitioners  will  be  glad  to  possess  this  little  manual,  which  gives  a  large  nuts> 
of  practical  hints  on  the  treatment  of  diseases  which  probably  make  up  the  larger  half  of 
every-day  practice.  The  translation  is  well  made,  and  explanations  ot  reference  to  German 
medicinal  preparations  are  given  with  proper  fulness.  —  Tne  Practitioner. 

DARLINGTON  (WILLIAM),  M.D. 

FLORA  CESTRICA;  OR,  HERBORIZING  COMPANION.  Con- 
taining all  the  Plants  of  the  Middle  States,  their  Linnaean  Arrangement, 
a  Glossary  of  Botanical  Terms,  a  complete  Index,  &c.  Third  Edition. 
i2'mo.  .......  .  $2.25 

DUCHENNE  (DR.  G.  B.). 

LOCALIZED    ELECTRIZATION.    AND    ITS    APPLICATION 
TO  PATHOLOGY  AND   THERAPEUTICS.     Translated  by  HER- 
BERT TIBBITS,  M.D.     With  Ninety-two  Illustrations.     Price     .     $3.00 
Duchenne's  great  work  is  not  only  a  well-nigh  exhaustive  treatise  on  the  medical  uses  of 
Electricity,  but  it  is  also  an  elaborate  exposition  of  the  different  diseases  in  which  Electric- 
ity has  proved  to  be  of  value  as  a  therapeutic  and  diagnostic  agent. 

PART  II.,  illustrated  by  chromolithographs  and  numerous  wood-cuts,  is  preparing. 

DURKEE  (SILAS),  M.D., 

Fellow  cf  the  Massachusetts  Medical  Society,  &c. 

GONORRHCEA   AND    SYPHILIS.     The  Fifth  Edition,  Revised 

and  Enlarged,  with  Portraits  and  Eight  Colored  Illustrations.     Octavo. 

Price     ....  .  -     $$.oo 

Dr.  Durkee's  work  impresses  the  reader  in  favor  of  the  author  by  its  general  tone,  the 


plaints  are  treated.  —  Lancet. 


DRUITT  (ROBERT),  F.R.C.S. 

THE  SURGEON'S  VADE-MECUM.  A  Manual  of  Modern  Sur- 
gery. The  Tenth  Revised  and  Enlarged  Edition,  with  350  Illustra- 
tions.    $5-°° 


15 

DALBY  (w.  B.),  F.  R.  C.  S., 

Aural  Surgeon  to  St.  George's  Hospital. 

LECTURES   ON   THE   DISEASES  AND  INJURIES  OF  THE 

-  EAR.      Delivered    at     St.     George's    Hospital.      With    Illustrations. 

Price      .          .          .          .          .          .          .          .          .          .          .     $1.50 

This  admirable  little  volume  by  Mr.  Dalby,  the  accomplished  aural  surgeon  to  St.  George's 
Hospital,  consists  of  eleven  lectures  delivered  by  him  at  that  institution.  "With  a  modes! 
aim,  tliis  work,  the  latest  issued  by  the  English  press  on  Aural  Surgery,  is  happy  in  concep- 
tion and  pleasantly  written ;  further,  it  shows  that  its  author  is  thoroughly  au  fait  in  his 
.specialty.  The  subject  of  which  the  volume  treats  is  handled  in  a  terse  style,  and  this,  if 
we  mistake  not,  will  make  it  acceptable  to  the  student  and  practitioner  who  have  a  just 
horror  of  unnecessary  details.  In  conclusion,  we  hope  that  we  have  succeeded  in  interesting 
our  readers  in  the  volume.  We  cordially  recommend  it  as  a  trustworthy  guide  in  the  treat- 
ment of  the  affections  of  the  ear.  The  book  is  moderate  in  price,  beautifully  illustrated  by 
wood-cuts,  and  got  up  in  the  best  style.  —  Glasgow  Medical  Journal. 

DUNGLISON  (ROBLEY),  M.D., 

Late  Professor  of  Institutes  of  Medicine,  &.C.,  in  the  Jefferson  Medical  College, 

A  HISTORY  OF  MEDICINE,  from  the  Earliest  Ages  to  the  Com- 
mencement  of  the  Nineteenth  Century.  Edited  by  his  son,  RICHARD 
J.  DUNGLISON,  M.D.  ........  $2.50 

ELLIS  (EDWARD),  M.D. 

Physician  to  the  Victoria  Hospital  for  Sick  Children,  &c, 

A  PRACTICAL  MANUAL  OF  THE  DISEASES  OF  CHIL- 
DREN, with  a  Formulary.  Second  Edition,  Revised  and  Improved. 

One  volume.  .         .         .         .         .         .         .         .         .     $2.75 

The  AUTHOR,  in  issuing  this  new  edition  of  his  book,  says:  "I  have  very  carefully  revised 
each  chapter,  adding  several  new  sections,  and  making  considerable  additions  where  the 
subjects  seemed  to  require  fuller  treatment,  without,  however,  sacrificing  conciseness  or 
unduly  increasing  the  bulk  of  the  volume." 

ELAM  (CHARLES),  M.D.,  F.R.C.P. 

ON  CEREBRIA  AND  OTHER  DISEASES  OF  THE  BRAIN. 

Octavo.          .         .         .         .         .         .         .         .         .         .     $2.50 

FOTHERGILL  (j.  MILNER),  M.D. 

THE  HEART  AND  ITS  DISEASES,  AND  THEIR  TREAT- 
MENT. With  Illustrations.  Octavo.  Price  .  .  $5-oo 

DIGITALIS.  Its  Mode  of  Action  and  its  Use,  illustrating  the 
Effect  of  Remedial  Agents  over  Diseased  Conditions  of  the  Heart. 
Price '.  .  .  $1.25 


FOX  (TILBURY),  M.  D.,  F.  R.  C.  P. 

Physician  to  the  Department  for  Skin  Diseases  in  University  College  Hospital, 

ATLAS  OF  SKIN  DISEASES.  Consisting  of  a  Series  of  Colored 
Illustrations,  in  Monthly  Parts,  together  with  Descriptive  Text  and 
Notes  upon  Treatment ;  each  Part  containing  Four  Plates,  reproduced  by 
Chromo-Lithography  from  the  work  of  Willan  &  Bateman,  or  taken  from 
Original  Sources.  Thirteen  Parts  now  ready.  Price,  per  Part,.  $2.00 
Full  Prospectuses  furnished  upon  application. 


16 

FENNER  (c.  s.VM.D.,  &c. 

VISION:  ITS  OPTICAL  DEFECTS,  and  the  Adaptation  of  Spec- 
tacles ;  embracing  Physical  Optics,  Physiological  Optics,  Errors  of  Re- 
fraction and  Defects  of  Accommodation,  or  Optical  Defects  of  the  Eye. 
With  74  Illustrations.  Selections  from  the  Test  Types  of  Jaeger  and 
Snellen,  etc.  Octavo.  Price  ......  $3.50 

FOSTER  (BALTHAZAR),  M.  D., 

Professor  of  Medicine  in  Queen's  College. 

LECTURES  AND  ESSAYS  ON  CLINICAL  MEDICINE.  Re- 
vised and  Enlarged  by  the  Author.  With  Engravings.  Octavo. 
Price  ...  .  $3.50 

FRANKLAND  (E.),  M.  D.,  F.  R.  S.,  &c. 

HOW  TO  TEACH  CHEMISTRY,  being  the  substance  of  Six 
Lectures  to  Science  Teachers.  Reported,  with  the  Author's. sanction, 
by  G.  George  Chaloner,  F.  C.  S.,  &c.  With  Illustrations  .  £1.25 

FEN  WICK  (SAMUEL),  M.D.,  F  R.C.P. 

THE  MORBID  STATES  OF  THE  STOMACH  AND  DUO- 
DENUM, AND  THEIR  RELATIONS  TO  THE  DISEASES  OF 
OTHER  ORGANS.  With  Ten  Plates.  .  .  $5.00 

FLINT  (AUSTIN),  M.D., 

Professor  of  the  Principles  and  Practice  of  Medicine,  &c.,  Bellevue  Hospital  College,  New  York, 

CLINICAL  REPORTS  ON  CONTINUED  FEVER.  Based  on 
an  Analysis  of  One  Hundred  and  Sixty-four  Cases,  with  Remarks  on 
the  Management  of  Continued  Fever;  the  Identity  of  Typhus  and 
Typhoid  Fever;  Diagnosis,  &c.,  &c.  Octavo.  Price  .  .  $2.00 

GANT  (FREDERICK  j.),  F.  R.  C.  S., 

Surgeon  to  the  Royal  Free  Hospital,  &c. 

DISEASES  OF  THE  BLADDER,  PROSTATE  GLAND,  AND 
URETHRA,  including  a  Practical  View  of  Urinary  Diseases,  Deposits, 
and  Calculi.  Fourth  Edition,  Revised  and  Enlarged.  With  New  Il- 
lustrations. Now  Ready.  Price'  ...  .  $4.00 

The  fact  that  a  fourth  edition  of  this  book  has  been  required  seems  to  be  sufficient  proof 
of  its  value.  The  author  has  carefully  revised  and  added  such  additional  matter  as  to  make 
it  more  complete  and  practically  useful. 

GODFREY  (BENJAMIN),  M.D.,  F.R.A.S. 

THE  DISEASES  OF  HAIR:  a  Popular  Treatise  upon  the  Affec- 
tions of  the  Hair  System.  .  .  .  .  .  .  #1.50 

GROSS  (SAMUEL  D.),  M.D., 

Professor  of  Surgery  in  the  Jefferson  Medical  College,  Philadelphia,  &c, 

AMERICAN  MEDICAL  BIOGRAPHY  OF  THE  NINETEENTH. 
CENTURY.  With  a  Portrait  of  BENJAMIN  RUSH,  M.D.  Octavo.  $3.50 


17 
GREENHOW  (E.  HEADLAM),  M.D., 

fellow  of  the  Royal  College  of  Physicians,  &c, 

ON  CHRONIC  BRONCHITIS,  Especially  as  Connected  with  Gout 

Emphysema,  and  Diseases  of  the  Heart.     Price       .         .         .     $2.00 

Of  all  works  yet  written  on  Chronic  Bronchitis,  this  is  undoubtedly  the  best.    The  style 

is  clear  and  to  the  point,  and  the  principles  of  pathology  and  treatment  eminently  correct 

and  practical.    It  is  a  positive  addition  to  our  medical  literature.  —  Journal  Psychological 

Medicine. 

BY  SAME  AUTHOR. 

ADDISON'S  DISEASE.  Being  the  Cronian  Lectures  for  1875. 
Delivered  before  the  Royal  College  of  Physicians.  Revised,  and  Illus- 
trated by  numerous  Cases  and  5  full-page  Colored  Engravings.  One 
volume,  octavo.  Price  .  .  *  .  .....  $3.  50 

BARLEY  (GEORGE),  M.  D.,  F.  R.  C.  P., 

Physician  to  University  College  Hospital, 

THE  URINE  AND  ITS  DERANGEMENTS:  With  the  Applica- 
tion of  Physiological  Chemistry  to  the  Diagnosis  and  Treatment  of 
Constitutional  as  well  as  Local  Diseases.  New  Revised  and  Enlarged 
Edition  preparing.  With  Engravings. 

We  have  here  a  valuable  addition  to  the  library  of  the  practising  physician; 
not  only  for  the  information  which  it  contains,  but  also  for  the  suggestive  way  in  which 
many  of  the  subjects  are  treated,  as  well  as  for  the  fact  that  it  contains  the  ideas  of  one  who 
thoroughly  believes  in  the  future  capabilities  of  Therapeutics  based  on  Physiological  facts, 
and  ia  the  important  service  to  be  rendered  by  Chemistry  to  Physiological  investigation. 

American  Journal  of  the  Medical  /Science. 

HEATH   (CHRISTOPHER),  F.  R.  C.  S., 

Surgeon  to  University  College  Hospital  and  Holme  Professor  of  Clinical  Surgery,  in  University  College, 

OPERATIVE  SURGERY.  Elegantly  Illustrated  by  20  Large  Col- 
ored Plates,  Imperial  Quarto  Size,  each  Plate  containing  several  Fig- 
ures, drawn  from  Nature  by  M.  Leveille,  of  Paris,  and  Colored  by  hand 
under  his  direction.  To  be  issued  in  Five  Quarterly  Parts.  Three  Parts 
now  ready.  Price,  per  Part,  .  .  .  .,  ,  .  $2-5° 

Full  Prospectuses  furnished  upon  application. 


HEWITT  (GRAILY),  M.  D., 

Physician  to  the  British  Lying-in  Hospital,  and  Lecturer  on  Diseases  of  Women  and  Children,  &c, 

THE  DIAGNOSIS,  PATHOLOGY,  AND  TREATMENT  OF 
DISEASES  OF  WOMEN,,  including  the  Diagnosis  of  Pregnancy. 
Founded  on  a  Course  of  Lectures  delivered  at  St.  Mary's  Hospital 
Medical  School.  The  Third  Edition,  Revised  and  Enlarged,  with 
new  Illustrations.  Octavo.  Price  in  Cloth  .  .  .  $5-°o 

"         Leather     .         .         .  6.00 

This  new  edition  of  Dr.  Hewitt's  book  has  been  so  much  modified,  that  it  may  be  considered 
substantially  a  new  book  ;  very  much  of  the  matter  has  been  entirely  rewritten,  and  the  whole 
work  has  been  rearranged  in  such  a  manner  as  to  present  a  most  decided  improvement  over 
previous  editions.  Dr.  Hewitt  is  the  leading  clinical  teacher  on  Diseases  of  Women  in  London, 
and  the  characteristic  attention  paid  to  Diagnosis  by  him  has  given  his  work  great  popularity 
there.  It  may  unquestionably  be  considered  the  most  valuable  guide  to  correct  Diagnosis  to 
be  found  in  the  English  language.  n 


18 
HILLIER  (THOMAS),  M.D., 

Physician  to  the  Hospital  for  Sick  Children,  &c. 

A  CLINICAL  TREATISE  ON  THE  DISEASES  OF  CHILDREN. 
Octavo.     Price      .........     $3.00 

We  have  said  enough  to  indicate  and  illustrate  the  excellence  of  Dr.  Hillier's  volume.  T\ 
is  eminently  the  kind  of  book  needed  by  all  medical  men  who  wish  to  cultivate  clinical 
accuracy  and  sound  practice.  — London  Lancet. 

HOLDEN  (LUTHER),  F.R.C.S. 

HUMAN  OSTEOLOGY,  comprising  a  Description  of  the  Bones 
with  Delineations  of  the  Attachments  of  the  Muscles,  &c.  With 
numerous  Illustrations.  Fifth  Edition,  carefully  Revised.  Price,  $6.00 

HOLDEN'S  MANUAL  OF  DISSECTIONS.     Price         .         $5.00 
HARRIS  (CHAPIN  A.),  M.D.,  D.D.S. 

Late  President  of  and  Professor  of  the  Principles  and  Practice  of  Dental  Surgery  in  the  Baltimore  College,  &.c, 

THE  PRINCIPLES  AND  PRACTICE  OF  DENTISTRY.  Tenth 
Revised  Edition,  In  great  part  rewritten,  rearranged,  and  with  many 
new  and  important  Illustrations.  Including — i.  Dental  Anatomy  and 
Physiology.  2.  Dental  Pathology  and  Therapeutics.  3.  Dental  Sur- 
gery. 4.  Dental  Mechanics.  Edited  by  P.  H.  AUSTEN,  M.D.,  Pro- 
fessor of  Dental  Science  and  Mechanism  in  the  Baltimore  College  of 
Dental  Surgery.  With  nearly  400  Illustrations,  including  many  new 
ones  made  especially  for  this  edition.  Royal  octavo.  Price,  in  cloth, 
$6.50;  in  leather  $7-5° 

This  new  edition  of  Dr.  Harris's  work  has  been  thoroughly  revised  in  all  its  parts  —  more 
so  than  any  previous  edition.  So  great  have  been  the  advances  in  many  branches  of  dentistry, 
that  it  was  found  necessary  to  rewrite  the  articles  or  subjects,  .and  this  has  been  done  in  the 
most  efficient  manner  by  Professor  Austen,  for  many  years  an  associate  and  friend  of  Dr. 
Harris,  assisted  by  Professor  Gorgas  and  Thomas  S.  Latimer,  M.D.  The  publishers  feel 
assured  that  it  will  now  be  found  the  most  complete  text-book  for  the  student  and  guide  for 
the  practitioner  in  the  English  language. 

SAME  AUTHOR. 

A  DICTIONARY  OF  MEDICAL  TERMINOLOGY,  DENTAL 
SURGERY,  AND  THE  COLLATERAL  SCIENCES.    Third  Edition, 
Carefully  Revised  and  Enlarged,  by  FERDINAND  J.  S.  GORGAS,  M.  D., 
D.D.S.,  Professor  of  Dental  Surgery  in  the  Baltimore  College,  &c.,  &c. 
Royal  octavo.     Price,  in  cloth,  $6.50;  in  leather          .         .         $7-5o 
The  many  advances  in  Dental  Science  rendered  it  necessary  that  this  edition  should  be 
thoroughly  revised,  which  has  been  done  in  the  most  satisfactory  manner  by  Professor  Gorgas, 
Dr.  Harris's  successor  in  the  Baltimore  Dental  College,  he  having  added  nearly  three  thou- 
sand new  words,  besides  making  many  additions  and  corrections.     The  doses  of  the  more 
prominent  medicinal  agents  have  also  been  added,  and  in  every  way  the  book  has  been  greatly 
improved,  and  its  value  enhanced  as  a  work  of  reference. 

HANDY  (WASHINGTON  R.),  M.D. 

Late  Professor  of  Anatomy,  &c,,  in  the  Baltimore  College. 

A  TEXT-BOOK  OF  ANATOMY,  AND  GUIDE  TO  DISSEC- 
TIONS. For  the  Use  of  Students  of  Medicine  and  Dental  Surgery. 
With  312  Illustrations.  Octavo.  Price  ....  $4.00 
Dr.  Handy's  work  was  prepared  with  special  reference  to  the  wants  of  the  Student  and 

Practitioner  of  Dental  Surgery.     Directing  particular  attention  to  the  Mouth,  it  shows  step 

by  step  the  important  Anatomical  and  Physiological  relations  which  it  has  with  each  and 

all  the  organs  and  functions  of  the  general  system. 


19 

HARDWICH  AND  DAWSON. 
HARDWICH'S  MANUAL  OF  PHOTOGRAPHIC  CHEMISTRY, 

With  Engravings.     Eighth  Edition.     Edited  and  Rearranged  by  G. 
DAWSON,  Lecturer  on  Photography,  &c.,  &c.     i2mo.       .         .     $2.00 

The  object  of  the  Editor  has  been  to  give  practical  instruction  in  this  fascinating  art,  and 
to  lead  the  novice  from  first  principles  to  the  higher  branches,  impressing  him  with  the  value 
of  care  and  exactness  in  every  operation. 

HEADLAND  (F.  w.),  M.  D., 

Fellow  of  the  Royal  College  of  Physicians,  &c,,  &c, 

ON  THE  ACTION  OF  MEDICINES  IN  THE  SYSTEM.  Sixth 
American  from  the  Fourth  London  Edition.  Revised  and  Enlarged. 
Octavo.  Price  .........  $3.00 

Dr.  Headland's  work  gives  the  only  scientific  and  satisfactory  view  of  the  action  of  medi- 
cine; and  this  not  in  the  way  of  idle  speculation,  but  by  demonstration  and  experiments, 
and  inferences  almost  as  indisputable  as  demonstrations.  It  is  truly  a  great  scientific  work 
in  a  small  compass,  and  deserves  to  be  the  hand-book  of  every  lover  of  the  Profession.  It 
has  received  the  approbation  of  the  Medical  Press,  both  in  this  country  and  in  Europe,  and 
is  pronounced  by  them  to  be  the  most  original  and  practically  useful  work  that  has  been 
issued  for  many  years. 

HILLES  (M.  w.), 

Formerly  Lecturer  on  Anatomy,  &c,,  at  Westminster  Hospital. 

THE  POCKET  ANATOMIST.  Being  a  Complete  Description  of 
the  Anatomy  of  the  Human  Body;  for  the  Use  of  Students.  Price,  in 
cloth,  $1.00;  in  Pocket-book  form $1.25 

HEATH  (CHRISTOPHER),  F.R.C.S., 

Surgeon  to  University  College  Hospital,  &c, 

INJURIES  AND  DISEASES  OF  THE  JAWS.  The  Jacksonian 
Prize  Essay  of  the  Royal  College  of  Surgeons  of  England,  1867.  Sec- 
ond Edition,  Revised,  with  over  150  Illustrations.  Octavo.  Price, 

$5.00 

SAME  AUTHOR. 
A  MANUAL  OF  MINOR  SURGERY  AND  BANDAGING,  for 

the  Use  of  House  Surgeons,  Dressers,  and  Junior  Practitioners.     With 
a  Formulae  and  Numerous  Illustrations.-     i6mo.       Price          .     $2.00 

HAYDEN  (THOMAS),  M.  D., 

Fellow  of  the  King  and  Queen's  College  of  Physicians,  &c.,  &c. 

THE  DISEASES  OF  THE  HEART  AND  AORTA.  With  Si 
Illustrations.  In  two  volumes,  Octavo,  of  over  1200  pages.  Price,  $8.00 

HUFELAND  (c.  w.),  M.D. 

THE  ART  OF  PROLONGING  LIFE.  Edited  by  ERASMUS  WIL- 
SON, M.  D.,  F.  R.S.,  &c.  i2mo.  Cloth.  .  $1.25 

The  highly  practical  character  of  Dr.  Hufeland's  book,  the  sound  advice  which  it  con- 
tains, and  its  elevated  moral  tone,  recommend  it  for  extensive  circulation,  both  among 
professional  and  non -professional  readers. 


20 
HEWSON  (ADDINELL,)  M.  D. 

Attending  Surgeon  Pennsylvania  Hospital,  &.c, 

EARTH  AS  A  TOPICAL  APPLICATION  IN  SURGERY. 
Being  a  full  Exposition  of  its  use  in  all  the  Cases  requiring  Topical 
Applications  admitted  in  the  Surgical  Wards  of  the  Pennsylvania  Hospi- 
tal during  a  period  of  Six  Months.  With  Illustrations.  Price  $2.50 


HUTCHINSON  (JONATHAN),  F.  R.  C.  S. 

Senior  Surgeon  to  the  London  Hospital, 

ILLUSTRATIONS    OF  CLINICAL  SURGERY.     Consisting  of 
Plates,   Photographs,  Wood-cuts,  Diagrams,  etc.,  Illustrating  Surgical 
Diseases,  Symptoms  and  Accidents,  also  Operations  and  other  Methods 
of  Treatment.     With    Descriptive    Letter-press.     4  Parts   now   ready. 
Price     ...........     $2.50 

rospectuses  furnished  upon  application. 


HODGE  (HUGH  L.),  M.  D. 

Emeritus  Professor  in  the  University  of  Pennsylvania, 

HODGE  ON  FCETICIDE,  OR  CRIMINAL  ABORTION. 
Fourth  Edition.  Price,  in  paper,  30  cents;  in  cloth,  .  .  .50 

HODGE'S  (H.  LENOX)  NOTE-BOOK  FOR  CASES  OF  OVARIAN 
TUMORS.  With  Diagrams,  etc.  Price,  ......  50 

HOLDEN  (EDGAR),  A.  M.,  M.  D, 

Of  Newark,  New  Jersey, 

CONTAINING  THREE  HUNDRED  ILLUSTRATIONS. 

THE  SPHYGMOGRAPH.  Its  Physiological  and  Pathological  In- 
dications. The  Essay  to  which  was  awarded  the  Stevens  Triennial 
Prize  in  the  College  of  Physicians  and  Surgeons  in  New  York,  April, 
1873.  Illustrated  by  Three  Hundred  Engravings  on  Wood.  One*  vol- 
ume octavo.  Price  .........  $2.00 

HOOD  (P.),  M.D. 

A  TREATISE  ON  GOUT,  RHEUMATISM,  AND  THE  ALLIED 
AFFECTIONS.  Crown  octavo.  ..  .  .  .  $4.25 

HANCOCK  (HENRY),  F.R.C.S. 

ON  THE  OPERATIVE  SURGERY  OF  THE  FOOT  AND 
ANKLE.  Numerous  Illustrations.  Octavo.  .  .  .  $6.00 

JONES  (T.  WHARTON),  F.R.S. 

DEFECTS  OF  SIGHT  AND  HEARING.  Their  Nature,  Causes, 
Prevention,  &c.  Second  Edition.  Price  .  .  .  $!-25 

JONES,  SIEVEKING,  AND  PAYNE. 

A  MANUAL  OF  PATHOLOGICAL  ANATOMY.  By  C.  HAND- 
FIELD  JONES,  M.  D.,  F.  R.  S.,  Physician  to  St.  Mary's  Hospital;  and 
EDWARD  H.  SIEVEKING,  M.D.,  F.R.C.^P.,  Physician  to  St.  Mary's  Hos- 
pital. A  New  and  Enlarged  Edition.  Edited  by  J.  F.  PAYNE,  M.B., 
F.R.C.P.,  Assistant  Physician  and  Lecturer  on  Morbid  Anatomy  at  St. 
Thomas's  Hospital.  With  Numerous  Illustrations.  .  .  $6.00 


21 
KIRBY  (E.  A.),  M.  D.,  M.  R.  C.  S.  Eng., 

Late  Physician  to  the  City  Dispensary, 

ON  THE  ADMINISTRATION  AND  VALUE  OF  PHOSPHO- 
RUS, as  a  Remedy  for  Loss  of  Nerve  Power,  Neuralgia,  Hysteria,  etc. 
With  Formulae  for  Combinations  with  Iron,  etc.  Second  Edition.  .50 

LAWSON  (GEORGE),  F.R.C.S,  i 

Surgeon  to  the  Royal  London  Ophthalmic  Hospital, 

DISEASES  AND  INJURIES  OF  THE  EYE,  THEIR  MEDICAL 
AND  SURGICAL  TREATMENT.  Containing  a  Formulary,  Test 
Types,  and  Numerous^  Illustrations.  Price  .  .  .  .  $2.50 

This  Manual  is  admirably  clear  and  eminently  practical.  The  reader  feels  that  he  is  in 
the  hands  of  a  teacher  who  has  a  right  to  speak  with  authority,  and  who,  if  he  may  be  said 
to  be  positive,  is  so  from  the  fulness  of  knowledge  and  experience,  and  who,  while  well  ac- 
quainted with  the  writings  and  labors  of  other  authorities  on  the  matters  he  treats  of,  has 
himself  practically  worked  out  what  he  teaches.  —  London  Medical  Times  and  Gazette. 

LEBER  &  ROTTENSTEIN  (DRS.). 

DENTAL  CARIES  AND  ITS  CAUSES.  An  Investigation  into 
the  Influence  of  Fungi  in  the  destruction  of  the  Teeth,  translated  by 
THOMAS  H.  CHANDLER,  D.M.D.,  Professor  of  Mechanical  Dentistry  in 
the  Dental  School  of  Harvard*  University.  With  Illustrations.  Octavo. 
Price  .  .  .  .  .  .  .  .  .  .  .  $1.50 

This  work  is  now  considered  the  best  and  most  elaborate  work  on  Dental  Caries.  It  is 
everywhere  quoted  and  relied  upon  as  authority  by  the  profession,  who  have  seen  it  in  the 
original,  and  by  authors  writing  on  the  subject. 

LEGG  (j.  WICKHAM),  M.  D. 

Member  of  the  Royal  College  of  Physicians,  &c, 

A  GUIDE  TO   THE   EXAMINATION  OF  THE  URINE.     For 

the  Practitioner  and  Student.   Fourth  Edition.  i6mo.  Cloth.  Price,  $0.75 

Dr.  Legg's  little  manual  has  met  with  remarkable  success;  the  speedy  exhaustion  of  two 
editions  has  enabled  the  author  to  make  certain  emendations  which  add  greatly  to  its  value. 
It  can  confidently  be  commended  to  the  student  as  a  safe  and  reliable  guide. 

LEARED  (ARTHUR),  M.D.,  F.R.C.P. 
IMPERFECT  DIGESTION:  ITS  CAUSES  AND  TREATMENT. 

The  Sixth  Edition,  Revised  and  Enlarged.       .         .         .         .     $1.75 

LESCHER  (F.  HARWOOD). 

THE  ELEMENTS  OF  PHARMACY.  For  Students.  The  Fourth 
Edition,  Revised  and  Enlarged.  Octavo '$3-°° 

KOLLMEYER  (A.  H.),  A.  M.,  M.  D. 

Professor  of  Materia  Medica  and  Therapeutics,  Montreal  College, 

CHEMIA  COARTATA ;  or,  The  Key  to  Modern  Chemistry.    With 

Numerous  Tables,  Tests,  &c.,  &c.     Price,        .         .         .         .     $2.25 


LIVEING  (EDWARD),  M.  D. 

ON    MEGRIM,    SICK-HEADACHE,    AND     SOME    ALLIED 
DISORDERS.     With  Colored  Plate.     Octavo    ....     $6.00 


22 
LEWIN   (DR.  GEORGE). 

Professor  at  the  Fr,-Wilh,  University)  and  Surgeon-in-Chief  of  the  Syphilitic  Wards  and  Skin  Diseases  of 

the  Charity  Hospital,  Berlin, 

THE  TREATMENT  OF  SYPHILIS  by  Subcutaneous   Sublimate 
Injections.    With  a  Lithographic  Plate  illustrating  the  Mode  and  Proper 
Place  of  administering  the  Injections,  and  of  the  Syringe  used  for  the 
purpose.     Translated  by  CARL  PRCEGLER,  M.D.,  late  Surgeon  in  the 
Prussian  Service,  and  E.  H.  GALE,  M.D.,  late  Surgeon  in  the  United 
States  Army.     Price       ........     $2.25 

The  great  number  of  cases  treated,  some  fourteen  hundred,  within  a  period  of  four  years, 
in  the  wards  of  the  Charity  Hospital,  Berlin,  only  twenty  of  which  were  returned  on 
account  of  Syphilitic  relapses,  certainly  entitles  the  method  of  treatment  advocated  by  this 
distinguished  syphilographer  to  the  attention  of  all  physicians  under  whose  notice  syphilitic 
eases  come. 

LlZARS  (JOHN),  M.  D. 

Late  Professor  of  Surgery  in  the  Royal  College  of  Surgeons,  Edinburgh. 

THE  USE  AND  ABUSE  OF  TOBACCO.  From  the  Eighth 
Edinburgh  Edition.  i2mo.  Price,  in  flexible  cloth,  .  $0.60 

This  little  work  contains  a  History  of  the  introduction  of  Tobacco,  its  general  characteris- 
tics ;  practical  observations  upon  its  effects  on  the  system ;  the  opinion  of  celebrated  profes- 
sional men  in  regard  to  it,  together  with  cases  illustrating  its  deleterious  influence,  A:c.,  &c. 

MACNAMARA  (c.). 

Surgeon  to  the  Ophthalmic  Hospital,  and  Professor  of  Ophthalmic  Medicine  in  the  Medical  College,  Calcutta. 

MANUAL   OF  THE   DISEASES   OF  THE  EYE.     The      Third 
Edition,   carefully   Revised;  with  Additions,  and  numerous    Colored 
Plates,  Diagrams  of  the    Eye,  many  Illustrations  on  Wood,  Snellen's 
Test  Types,  &c.,  &c.     Price  ......     $4.50 

"  This  work  when  first  published  took  its  place  in  medical  literature  as  the  most  complete, 
condensed,  and  well-arranged  manual  on  ophthalmic  surgery  in  the  English  language. 
Arranged  especially  for  medical  students,  it  became,  however,  the  work  of  reference  for  the 
busy  practitioner,  who  could  obtain  nearly  all  that  was  best  worth  knowing  on  this  subject, 
tersely  stated,  and  easily  found  by  the  aid  of  the  excellent  marginal  notes  on  the  contents 
of  the  paragraphs."  —  Philadelphia  Medical  Times. 

MACKENZIE  (MORELL),  M.  D. 

Physician  to  the  Hospital  for  Diseases  of  the  Throat,  London,  &c, 

GROWTHS  IN  THE  LARYNX.     Their  History,  Causes,  Symp- 
toms, Diagnosis,  Pathology,  Prognosis,  and  Treatment.     With  Reports 
and  Analysis  of  One  Hundred  Consecutive  Cases  treated  by  the  Author ; 
and  a  Tabular  Statement  of  every  published  case  treated  since  the  in- 
vention of  the    Laryngoscope.       With  numerous   Colored  and   other 
Illustrations.     Octavo.     Price         ......     $3-00 

Dr.  Mackenzie's  position  has  given  him  great  advantages  and  a  large  experience  in  the 

treatment  of  Diseases  of  the  Throat,  and  for  many  years  he  has  been  regarded  as  a  leading 

authority  in  this  department  of  Surgery.     The  Illustrations  have  been  prepared  with  great 

care  and  expense. 

OTHER  WORKS  BY  SA.ME  AUTHOR. 

THE  LARYNGOSCOPE  IN  DISEASES  OF  THE  THROAT. 
With  an  Appendix  on  Rhinoscopy,  and  an  Essay  on  Hoarseness  and 
Loss  of  Voice.  With  Additions  by  J.  SOLIS  COHEN,  and  Numerous 
Illustrations  on  Wood  and  Stone.  Price  .... 

PHARMACOPCEIA  OF   THE*" HOSPITAL   for   Diseases   of  the 
Throat;  with  One  Hundred  and  Fifty  Formulae  for  Gargles,  &c.,  &c. 
Price     .         .         .         .         .         .         .         .         .          .          .     $1.25 

9 


23 

MEIGS  AND  PEPPER. 

A  PRACTICAL  TREATISE  ON  THE   DISEASES  OF  CHIL- 
DREN.    By  J.  FORSYTH  MEIGS,  M.D.,  Fellow  of  the  College  of  Physi- 
cians of  Philadelphia,  &c.,  &c.,  and  WILLIAM  PEPPER,  M.D.,  Physician 
to  the  Philadelphia  Hospital,  &c.     Sixth  Edition,  thoroughly  Revised 
and  greatly  Enlarged,  forming  a  Royal  Octavo  Volume  of  over  1000 
pages.     Price,  bound  in  cloth,  $6.00;  leather          .         .         .     $7.00 
It  is  the  most  complete  work  on  the  subject  in  our  language.     It  contains  at  once  the  re- 
sults of  personal,  and  the  experience  of  others.     Its  quotations  from  the  most  recent  author- 
ities, at  home  and  abroad,  are  ample,  and  we  think  the  authors  deserve  congratulations  for 
having  produced  a  book  unequalled  for  the  use  of  the  student  and  indispensable  as  a  work 
of  reference  for  the  practitioner.  —  American  Medical  Journal. 

MURPHY  (JOHN  G.),  MJD. 

A  REVIEW  OF  CHEMISTRY  FOR  STUDENTS.  Adapted  to 
the  Courses  as  Taught  in  the  Principal  Medical  Schools  in  the  United 
States. 1 1. 25 

MENDENHALL  (GEORGE),  M.D., 

Professor  of  Obstetrics  in  the  Medical  College  of  Ohio,  &c. 

MEDICAL  STUDENT'S  VADE  MECUM.  A  Compendium  of 
Anatomy,  Physiology,  Chemistry,  the  Practice  of  Medicine,  Surgery, 
Obstetrics,  Diseases  of  the  Skin,  Materia  Medica,  Pharmacy,  Poisons, 
&c.,  &c.  Eleventh  Edition,  Revised  and  Enlarged,  with  224  Illustra- 
tions. .  .  .  .  .  .  .  .  .  .  $2.50 

MAXSON  (EDWIN  R.),  M.D., 

Formerly  Lecturer  on  the  Practice  of  Medicine  in  the  Geneva  Medical  College,  &c, 

THE  PRACTICE  OF  MEDICINE.      ...  .     $4.00 

MARSH  AlZ^joHN),  F.R.S7 

Professor  of  Surgery,  University  College,  London, 

PHYSIOLOGICAL  DIAGRAMS.  Life-size,  and  Beautifully  Col- 
ored. An  Entirely  New  Edition,  Revised  and  Improved,  illustrating 
the  whole  Human  Body,  each  Map  printed  on  a  single  sheet  of  paper, 
seven  feet  long  and  three  feet  nine  inches  broad. 

No.  1.  The  Skeleton  and  Ligaments. 


No.  2.  The  Muscles,  Joints,  and  Animal  Me- 
chanics. 

No.  3.  The  Viscera  in  Position.  —  The  Struc- 
ture of  the  Lungs. 

No.  4.  The  Organs  of  Circulation. 

No.  5.  The  Lymphatics  or  Absorbents. 

No.  6.  The  Digestive  Organs. 


No.    7.  The  Brain  and  Nerves. 

No.    8.  The  Organs  of  the  Senses  and  Organs 

of  the  Voice.     Plate  1. 
No.    9.  The  Organs  of  the  Senses.     Plate  2. 
No.  10.  The   Microscopic    Structure  of   the 

Textures.     Plate  1. 
No.  11.  The    Microscopic    Structure  of  the 

Textures.    Plate  2. 


Price  of  the  Set,  Eleven  Maps,  in  Sheets,     .          .                            .  $50.00 
"             "                   "                  "          handsomely  Mounted  on 

Canvas,  with  Rollers,  and  varnished,     .....  $80.00 

An  Explanatory  Key  to  the  Diagram.     Price         ....  50 

MADDEN  (T.  M.),  M.  D. 

Author  of  "  Climatology  and  the  Use  of  Mineral  Waters," 

THE  HEALTH  RESORTS  OF  EUROPE  AND  AFRICA  for  the 

Treatment  of  Chronic  Diseases.  A  Hand -Book  the  result  of  the 
Author's  own  Observations  during  several  years  of  Health-Travel  in 
many  Lands,  containing,  also,  the  substance  of  the  Author's  former 
Work  on  CLIMATOLOGY  AND  THE  USE  OF  MINERAL  WATERS.  Octavo. 
Price  &no 


24 
MAUNDER  (c.  F.),  F.  R.  C.  S. 

Surgeon  to  the  London  Hospital;  formerly  Demonstrator  of  Anatohiy  at  Guy's  Hospital. 

OPERATIVE  SURGERY.  Second  Edition,  with  One  Hundred 
and  Sixty- four  Engravings  on  Wood.  Price  .  .  .  $2.50 

BY  SAME  AUTHOR. 

SURGERY  OF  THE  ARTERIES,  including  Aneurisms,  Wounds, 
Haemorrhages,  Twenty-seven  Cases  of  Ligatures,  Antiseptic,  etc.  With 
1 8  Illustrations.  Price $2.00 

MAYNE  (R.  G.),  M.  D.,  AND  MAYNE  (j.),  M.  D. 
MEDICAL  VOCABULARY:  An  Explanation  of  all  Names, 
Synonyms,  Terms,  and  Phrases  used  in  Medicine  and  the  Relative 
Branches  of  Medical  Science,  giving  their  correct  Derivation,  Meaning, 
Application,  and  Pronunciation.  Intended  especially  as  a  book  of 
reference  for  Physicians  and  Students.  Fourth  Edition,  Revised  and 
Enlarged.  Post  8vo.  450  pages.  Price  .  .  .  .  $3-oo 

MARTIN  (JOHNH.). 

Author  of  Microscopic  Objects,  &c, 

A  MANUAL  OF  MICROSCOPIC  MOUNTING.  With  Notes  on 
the  Collection  and  Examination  of  Objects,  and  upwards  of  One  Hun- 
dred Illustrations  on  Stone  and  Wood,  drawn  by  the  Author. 
Price  ...........  $3.00 

MEADOWS  (ALFRED),  M.  D. 

Physician  to  the  Hospital  for  Women,  and  to  the  General  Lying-in  Hospital,  &c, 

MANUAL  OF  MIDWIFERY.  A  New  Text-Book.  Including  the 
Signs  and  Symptoms  of  Pregnancy,  Obstetric  Operations,  Diseases  of 
the  Puerperal  State,  &c.,  &c.  Second  American  from  the  Third  Lon- 
don Edition.  Revised  and  Enlarged.  With  145  Illustrations. 

This  book  is  especially  valuable  to  the  Student  as  containing  in  a  condensed  form  a  large 
amount  of  valuable  information  on  the  subject  which  it  treats.  It  is  also  clear  and  methodi- 
cal in  its  arrangement,  and  therefore  useful  as  a  work  of  reference  for  the  practitioner.  The 
Hlustratiors  are  numerous  and  well  executed. 

MILLER  (JAMES),  F.R.C.S. 

Professor  of  Surgery  University  of  Edinburgh. 

ALCOHOL,  ITS  PLACE  AND  POWER.     From  the  Nineteenth 

Glasgow  Edition.      121110.      Cloth  flexible.     Price   .         .         .     $0.75 

This  work  was  prepared  fcy  Professor  Miller  at  the  special  request  of  the  Scottish  Temper- 
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view  of  the  subject  that  could  be  freely  disseminated  among  all  classes. 

MILLER  AND  LIZARS. 

ALCOHOL:  Its  Place  and  Power.  By  JAMES  MILLER,  F.R.S.E.,  late 
Professor  of  Surgery  in  the  University  of  Edinburgh,  &c. — THE  USE 
AND  ABUSE  OF  TOBACCO.  By  JOHN  LIZARS,  late  Professor  to  the 
Royal  College  of  Surgeons,  &c.  The  Two  Essays  in  One  Volume. 
i2mo.  ..........  $1.00 


25 

MARSDEN   (ALEXANDER),  M.D. 

A  NEW  AND  SUCCESSFUL  MODE  OF  TREATING  CERTAIN 
FORMS  OF  CANCER.  Second  Edition,  Colored  Plates.  .  $3.50 

MACDONALD  (j.  D.),  M.  D., 

Deputy  Inspector-General  of  Hospitals,  Assistant  Professor  of  Hygiene,  Army  Medical  School,  &c, 

A  GUIDE  TO  THE  MICROSCOPICAL  EXAMINATION  OF 
DRINKING  WATER.  With  Twenty  Full-page  Lithographic  Plates, 
References,  Tables,  etc.,  etc.  Octavo.  Price  .  .  .  $3.00 

NORRIS   (GEORGE  w.),  M.  D., 

Late  Surgeon  to  the  Pennsylvania  Hospital,  &.c, 

CONTRIBUTIONS     TO     PRACTICAL    SURGERY,    including 

numerous  Clinical  Histories,  Drawn  from  a  Hospital  Service  of  Thirty 
Years.     In  one  Volume,  Octavo.     Price          .         .         .         .     $4.00 

OVERMAN  (FREDERICK), 

Mining  Engineer,  &c. 

PRACTICAL  MINERALOGY,  ASSAYING  AND  MINING. 
With  a  Description  of  the  Useful  Minerals,  and  Instructions  for  Assay- 
ing, according  to  the  Simplest  Methods.  .  .  .  .  $1.25 

PHYSICIAN'S  VISITING  LIST,  PUBLISHED  ANNUALLY. 

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50       "             "               "                                  "  .  .  .  1.25 

75       "           •"              "            "                  "  .  .  .  1.50 

100       "             "               "             "                   "  .  .  .  2.00 

^O          "  «    2V01S.    i^    tQJUnel  -  .  2.50 

(  July  to  Dec.  j 

100       "  "   2  vols.  •<  i  ?'  i°  i^]  e  !•        "  -3.00 

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,  INTERLEAVED    EDITION. 

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^  <*    nr~> 


,      f  Ian.  to  Tune  )      ,, 
5°  2Vols-|jl,lytoDec.| 


This  Visiting  List  has  now  been  published  Twenty-four  Yearn,  and  has  met  with  such  uni- 
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from  year  to  year. 

POWER,  HOLMES,  ANSTIE,  AND  BARNES. 
REPORTS  ON  THE  PROGRESS  OF  MEDICINE  AND  SUR- 
GERY, PHYSIOLOGY,  OPHTHALMIC  MEDICINE,  MID- 
WIFERY, ^DISEASES  OF  WOMEN  AND  CHILDREN,  MATERIA 
MEDICA,  &c.  .Edited  for  the  Sydenham  Society  of  London.  Octavo. 
Price  ........  "...  $2.00 


26 
PARKES  (EDWARD  A.),  M.  D., 

Professor  of  Military  Hygiene  in  the  Army  Medical  School,  &c. 

A  MANUAL  OF  PRACTICAL  HYGIENE.  The  Fourth  Revised 
and  Enlarged  Edition,  for  Medical  Officers  of  the  Army,  Civil  Medical 
Officers,  Boards  of  Health,  &c.,  &c.  With  many  Illustrations.  One 
Volume  Octavo.  Price  .......  $6.00 

This  work,  previously  unrivalled  as  a  text-book  for  medical  officers  of  the  army,  is  now 
equally  unrivalled  as  a* text-book  for  civil  medical  officers.  The  first  book  treats  i'n  succes- 
sive chapters  of  water,  air,  ventilation,  examination  of  air,  food,  quality,  choice,  and  cooking 
of  food,  beverages,  and  condiments  ;  soil,  habitations,  removal  of  excreta,  warming  of  houses, 
exercise,  clothing,  climate,  meteorology,  individual  hygienic  management,  disposal  of  the 
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book  is  devoted  to  the  service  of  the  soldier,  but  is  hardly  less  instructive  to  the  civil -officer 
of  health.  It  is,  in  short,  a  comprehensive  and  trustworthy  text-book  of  hygiene  for  the 
scientific  or  general  reader. —  London  Lancet. 

POWER  (HENRY),  M.  B.,  F.  R  .C.  S., 

Senior  Ophthalmic  Surgeon  to  St,  Bartholomew's  Hospital. 

THE  STUDENT'S  GUIDE  TO  THE  DISEASES  OF  THE  EYE. 

With  Engravings.     Preparing. 

PENNSYLVANIA  HOSPITAL  REPORTS. 

EDITED  BY  A  COMMITTEE  OF  THE  HOSPITAL  STAFF. 
J.  M.  DA  COSTA,  M.  D.,  and  WILLIAM  HUNT,  M.  D.  Vols.  i  and  2  \  each 
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are  all  valuable  contributions  to  the  literature  of  medicine,  reflecting  great  credit  upon  their 
authors.  The  work  is  one  of  which  the  Pennsylvania  Hospital  may  well  be  proud.  It  will 
do  much  towards  elevating  the  profession  of  this  country. —  American  Journal  of  Obstetrics. 

PAGET  (JAMES),  F.  R.  S., 

Surgeon  to  St,  Bartholomew's  Hospital,  &c, 

SURGICAL  PATHOLOGY.     Lectures  delivered  at  the  Royal  Col- 
lege of  Surgeons  of  England.      Third  London  Edition,  Edited   and 
Revised  by  WILLIAM  TURNER,   M.  D.     With  Numerous    Illustrations. 
Price,  in  cloth,  $7.50;   in  leather  ......     $8.50 

A  new  and  revised  edition  of  Mr.  Paget's  Classical  Lectures  needs  no  introduction  to  our 
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evidence  that  this  edition  has  been  "  carefully  revised." — American  Medical  Journal. 

PEREIRA  (JONATHAN),  M.  D.,  F.  R.  S.,  &c. 
PHYSICIAN'S  PRESCRIPTION  BOOK.  Containing  Lists  of 
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with  Explanatory  Notes,  the  Grammatical  Constructions  of  Prescrip- 
tions, Rules  for  the  Pronunciation  of  Pharmaceutical  Terms,  a  Proso- 
diacal  Vocabulary  of  the  Names  of  Drugs,  &c.,  and  a  Series  of  Abbre- 
viated Prescriptions  illustrating  the  use  of  the  preceding  terms,  &c.  ;  to 
which  is  added  a  Key,  containing  the  Prescriptions  in  an  unabbreviated 
Form,  with  a  Literal  Translation,  intended  for  the  use  of  Medical  and 
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in  cloth,  $1.25  ;  in  leather,  with  Tucks  and  Pocket,  .  .  $1.50 


27 

PROCTOR  (BARNARD  s.). 

PRACTICAL  PHARMACY.  A  Course  of  Lectures  comprising 
Descriptions  of  General  Processes,  Lessons  in  Dispensing,  Pharmaco- 
poeia! Testing,  Qualitative  and  Quantitative,  &c.  With  Illustrations. 
Octavo.  Price  .  .  .  .  .  .  .  .  $5-oo 

PARKER  (LANGSTON),  F.  R.  C.  S.  L. 
THE  MODERN  TREATMENT  OF   SYPHILITIC  DISEASES. 

Containing  the  Treatment  of  Constitutional  and  Confirmed  Syphilis, 
with  numerous  Cases,  Formulae,  &c.,&c.    Fifth  Edition,  Enlarged.    $4.25 

PRINCE  (DAVID),  M.  D. 

PLASTIC  AND  ORTHOPEDIC  SURGERY.  Containing  i.  A 
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pedic Surgery  up  to  the  Year  1871.  2.  A  New  Classification  and  Brief 
Exposition  of  Plastic  Surgery.  With  numerous  Illustrations.  3.  Ortho- 
pedics: A  Systematic  Work  upon  the  Prevention  and  Cureof  Deformities. 
With  numerous  Illustrations.  Octavo.  Price  .  .  .  $4.50 

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book.  —  Medical  and  Surgical  Reporter. 

SAME  AUTHOR. 
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made  to  the  Illinois  State  Medical  Society.     With  Illustrations.     Price, 


PIESSE  (G.  w.  SEPTIMUS), 

Analytical  Chemist, 

WHOLE  ART  OF  PERFUMERY.     And  the  Methods  of  Obtaining 

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&c.  Second  American  from  the  Third  London  Edition.  With  Illus- 
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PIGGOTT  (A.  SNOWDEN),  M.  D., 

Practical  Chemist. 

COPPER  MINING  AND  COPPER  ORE.  Containing  a  full  Descrip- 
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DIABETES.  Researches  on  its  Nature  and  Treatment.  Third  Re- 
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Price,  per  dozen     . 


28 
RINDFLEISCH   (DR.  EDWARD), 

Professor  of  Pathological  Anatomy,  University  of  Bonn, 

TEXT-BOOK  OF  PATHOLOGICAL  HISTOLOGY.  An  Intro, 
duction  to  the  Study  of  Pathological  Anatomy.  Translated  from  the 
German,  by  WM.  C.  KLOMAN,  M.D.,  assisted  by  F.  T.  MILES,  M.D., 
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tions. Octavo^  Price,  bound  in  Cloth,  ....  $6.00 

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which  no  pathological  writer  or  student  can  atibrd  to  neglect,  who  desires  to  interpret  aright 
pathological  structural  changes,  and  his  book  is  consequently  well  known  to  readers  of  Ger- 
man medical  literature.  What  makes  it  especially  valuable  is  the  fact  that  it  was  originated, 
as  its  author  himself  tells  us,  more  at  the  microscope  than  at  the  writing-table.  Altogether 
the  book  is  the  result  of  honest  hard  labor.  It  is  admirably  as  well  as  profusely  illustrated, 
furnished  with  a  capital  Index,  and  got  up  in  a  way  that  is  worthy  of  what  must  continue 
to  be  the  standard  book  of  the  kind." 

ROBERTS  (FREDERICK  T.).,  M.  D.,  B.  Sc. 

Assistant  Physician  and  Teacher  of  Clinical  Medicine  in  the  University  College  Hospital  j  Assistant  Physician 
Brompton  Consumption  Hospital,  &c, 

A  HAND-BOOK   OF  THE  THEORY   AND   PRACTICE   OF 
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Leather,     6.00 

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works  on  Practice  or  of  the  various  special  monographs. 


REYNOLDS  (j.  RUSSELL),  M.  D.,  F.  R.  S., 

Lecturer  on  the  Principles  and  Practice  of  Medicine,  University  College,  London, 

LECTURES  ON  THE  CLINICAL  USES  OF  ELECTRICITY. 
Delivered  at  University  College  Hospital.  Second  Edition,  Revised 
and  Enlarged.  Price 1 1-25 

RYAN  (MICHAEL),  M.  D. 

Member  of  the  Royal  College  of  Physicians, 

PHILOSOPHY  OF  MARRIAGE,  in  its  Social,  Moral,  and  Physi* 
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11 


29 

RADCLIFFE  (CHARLES  BLAND),  M.D., 

Fellow  of  the  Royal  College  of  Physicians  of  London,  &c. 

LECTURES   ON   EPILEPSY,   PAIN,    PARALYSIS,   and   other 

Disorders  of  the  Nervous  System.     With  Illustrations.     .         .     $2.00 

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throw  much  light  upon  the  Physiology  and  Pathology  of  the  Nervous  System. —  Canada 
Medical  Journal. 

ROBERTSON  (A.),  M.D.,  D.D.S. 

A   MANUAL   ON    EXTRACTING    TEETH.     Founded  on    the 

Anatomy  of  the  Parts  involved  in  the  Operation,  the  kinds  and  proper 
construction  of  the  instruments  to  be  used,  the  accidents  likely  to  occur 
from  the  operation,  and  the  proper  remedies  to  retrieve  such  accidents. 
A  New  Revised  Edition.  . 

The  author  is  well  known  as  a  contributor  to  the  literature  of  the  profession,  and  as  a 
clear,  terse,  and  practical  writer.  The  subject  is  one  to  which  he  has  devoted  considerable 
attention,  and  is  treated  with  his  usual  care  and  ability.  The  work  is  valuable  not  only 
to  the  dental  student  and  practitioner,  but  also  to  the  medical  student  and  surgeon.  —  Dental 
Cosmos. 

REESE  (JOHN  j.),  M.D., 

Professor  of  Medical  Jurisprudence  and  Toxicology  in  the  University  of  Pennsylvania, 

AN  ANALYSIS  OF  PHYSIOLOGY.  Being  a  Condensed  View 
of  the  most  important  Facts  and  Doctrines,  designed  especially  for  the 
Use  of  Students.  Second  Edition,  Enlarged.  .  .  .  $1.50 

SAME  AUTHOR. 

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RICHARDSON  (JOSEPH),  D.D.S. 

Late  Professor  of  Mechanical  Dentistry,  &c,,  &c, 

A  PRACTICAL  TREATISE  ON  MECHANICAL  DENTISTRY. 

Second  Edition,  much  Enlarged.  With  over  150  beautifully  executed 
Illustrations.  Octavo.  Price,  in  cloth,  $4.00 ;  in  leather,  .  $4.50 

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terfered with  most  elaborate  details  where  this  is  necessary ;  and  the  numerous  and  beautifully 
executed  wood-cuts  with  which  it  is  illustrated  make  the  volume  as  attractive  as  its  instruc- 
tions are  easily  understood.  — Edinburgh  Med.  Journal. 

ROBERTS  (LLOYD  D.),  M.D., 

Vice-President  of  the  Obstetrical  Society  of  London,  Physician  to  St.  Mary's  Hospital,  Manchester, 

THE  STUDENT'S  GUIDE  TO  THE  PRACTICE  OF  MID- 
WIFERY, With  95  Illustrations.  Price  .  .  $2.25 

RUTHERFORD  (WILLIAM),  M.  D.,  F.  R.  S.  E. 

Professor  of  the  Institutes  of  Medicine  in  the  University  of  Edinburgh, 

OUTLINES  OF  PRACTICAL  HISTOLOGY  FOR  STUDENTS 
AND  OTHERS.  Second  Edition,  Revised  and  Enlarged.  With  Illus- 
trations, &c.  Price -  $2.00 


30 

RIGBY  AND  MEADOWS. 

DR.  RIGBY'S  OBSTETRIC  MEMORANDA.  Fourth  Edition, 
Revised  and  Enlarged,  by  ALFRED  MEADOWS,  M.  D.,  Author  of  "A 
Manual  of  Midwifery,"  &c.  Price  .  .  .  .  .  .  .50 

ROYLE'S  MANUAL  OF  MATERIA  MEDICA  AND  THERA- 
PEUTICS. The  Sixth  Revised  and  Enlarged  Edition.  Containing 
all  the  New  Preparations  according  to  the  New  British,  American, 
French,  and  German  Pharmacopoeias,  the  New  Chemical  Nomencla- 
ture, etc.,  etc.  Edited  by  JOHN  HARLEY,  M.  D..  F.  R.  C.  P.,  Assistant 
Physician  and  Lecturer  on  Physiology  at  St.  Thomas's  Hospital.  With 
139  Illustrations,  many  of  them  new.  One  vol.,  Demy  Octavo.  $6.00 

RUPPANER  (ANTOINE),  M.  D. 

THE  PRINCIPLES  AND  PRACTICE  OF  LARYNGOSCOPY 
AND  RHINOSCOPY  IN  DISEASES  OF  THE  THROAT,  &c. 

Fifty-nine  Illustrations.      Price         .          .          .          .          .          .     $1.50 

SANDERSON,  KLEIN,  FOSTER,  AND  BRUNTON. 

A  HAND-BOOK  FOR  THE  PHYSIOLOGICAL  LABORATORY. 

Being  Practical  Exercises  for  Students  in  Physiology  and  Histology,  by 

E.  KLEIN,   M.  D.,  Assistant  Professor  in  the  Pathological  Laboratory 
ot   the   Brown   Institution,  London;    J.    BURDON-SANDERSON,  M.  D., 

F.  R.  S.,   Professor  of  Practical  Theology  in  University  College,  Lon- 
don; MICHAEL  FOSTER,  M.D.,  F.R.S.,  Fellow  of  and  Prelector  of  Phys- 
iology in  Trinity  College,  Cambridge;  and  T.  LAUDERBRUNTON,  M.D., 
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tholomew's Hospital.     Edited  by  J.  BURDON-SANDERSON.     The  Illus- 
trations  consist    of    One    Hundred    and    Twenty-three   octavo  pages, 
including    over   Three    Hundred  and  Fifty  Figures,  with  appropriate 
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THE  MEDICAL  ADVISER  IN  LIFE  ASSURANCE.    Price  $2  25 

This  book  supplies,  in  a  concise  and  available  form,  such  facts  and  figures  as  are  required 
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contingencies  upon  which  life  insurance  rests. 

SWAIN  (WILLIAM  PAUL),  F.R.C.S., 

Surgeon  to  the  Royal  Albert  Hospital,  Devonport, 

SURGICAL  EMERGENCIES:  A  MANUAL  CONTAINING 
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volume,  121110.  Clolh.  Price $2.00 


31 
STILLE  (ALFRED),  M.  D. 

Professor  of  the  Theory  and  Practice  of  Medicine  in  the  University  of  Pennsylvania,  &c. 

EPIDEMIC  MENINGITIS  ;  or,  Cerebro-Spinal  Meningitis.  In  one 
volume,  Octavo.  .  .  .  .  .  .  .  .  $2.00 

This  monograph  is  a  timely  publication,  comprehensive  in  its  scope,  and  presenting  within 
a  small  compass  a  fair  digest  of  our  existing  knowledge  of  the  disease,  particularly  accept- 
able at  the  present  time.  It  is  just  such  a  one  as  is  needed,  and  may  betaken  as  a  model 
for  similar  works.  —  American  Journal  Medical  Sciences. 

SMITH  (WILLIAM  ROBERT), 

Resident  Surgeon,  Hants  County  Hospital. 

LECTURES  ON  THE  EFFICIENT  TRAINING  OF  NURSES 
FOR  HOSPITAL  AND  PRIVATE  WORK.  With  Illustrations. 
121110.  Cloth.  Price  ........  $2.25 

SCHULTZE  (DR.  B.  s.), 

Professor  of  Midwifery  at  the  University  of  Jena, 

LECTURE  DIAGRAMS  FOR  INSTRUCTION  IN  PREG- 
NANCY AND  MIDWIFERY.  Twenty  Plates  of  the  largest  Imperial 
size,  printed  in  colors.  Drawn  and  Edited  with  Explanatory  Notes, 
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SANSOM  (ARTHUR  ERNEST),  M.B., 

Physician  to  King's  College  Hospital,  &c. 

CHLOROFORM.     Its  Action  and  Administration.     Price         $2.00 
BY  SAME  AUTHOR. 

LECTURES  ON  THE  PHYSICAL  DIAGNOSIS  OF  DISEASES 
OF  THE  HEART,  intended  for  Students  and  Practitioners,  $1.50 

SCANZONI  (F.  w.  VON), 

Professor  in  the  University  of  Wurzbur<r. 

A  PRACTICAL  TREATISE  ON  THE  DISEASES  OF  THE 
SEXUAL  ORGANS  OF  WOMEN.  Translated  from  the  French. 
By  A.  K.  GARDNER,  M.D.  With  Illustrations.  Octavo.  .  $5.00 

STOKES  (WILLIAM), 

Regius  Professor  of  Physic  in  the  University  of  Dublin.! 

THE  DISEASES  OF  THE  HEART  AND  THE  AORTA. 
Octavo.  ..........  -°o 


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SWERINGEN   (HIRAM    v.). 

Member  American  Pharmaceutical  Association,  &c, 

PHARMACEUTICAL   LEXICON.     A  Dictionary  of  Pharmaceu- 
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SEWILL  (H.  E.),  M^RTc.  S.,  Eng.,  L.  D.  S., 

Dental  Surgeon  to  the  West  London  Hospital. 

THE  STUDENT'S  GUIDE  TO  DENTAL  ANATOMY  AND 
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SHEPPARD  (EDGAR),  M.  D. 

Professor  of  Psychological  Medicine  in  King's  College,  London, 

MADNESS,  IN  ITS  MEDICAL,  SOCIAL,  AND  LEGAL  AS- 
PECTS. A  series  of  Lectures  delivered  at  King's  College,  London. 
Octavo.  Price £2.50 

SAVAGE  (HENRY),  M.  D.,  F.  R.  C.  S. 

Consulting  Physician  to  the  Samaritan  Free  Hospital,  London. 

THE  SURGERY,  SURGICAL  PATHOLOGY,  and  Surgical  Anat- 
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SAME  AUTHOR. 

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SUTTON  (FRANCIS),  F.  C.  S. 

A  SYSTEMATIC  HAND-BOOK  OF  VOLUMETRIC  ANALYSIS, 

or  the  Quantitative  Estimation  of  Chemical  Substances  by  Measure, 
Applied  to  Liquids,  Solids,  and  Gases.  Third  Edition,  enlarged. 
With  numerous  Illustrations.  Now  Ready.  Price  .  .  $5-5° 

SMITH  (EUSTACE),  M.D. 

Physician  to  the  East  London  Hospital  for  Diseases  of  Children,  &c, 

CLINICAL   STUDIES   OF    DISEASES   OF  THE   LUNGS   IN 
CHILDREN.     Price $2.50 


33 

TANNER  (THOMAS  HAWKES),  M.D.,  F.R.C.P.,  &c. 

THE  PRACTICE  OF  MEDICINE.  Sixth  American  from  the  last 
London  Edition.  Revised,  much  Enlarged,  and  thoroughly  brought  up 
to  the  present  time.  With  a  complete  Section  on  the  Diseases  Peculiar 
to  Women,  an  extensive  Appendix  of  Formulae  for  Medicines,  Baths, 
&c.,-&c.  Royal  Octavo,  over  noo  pages.  Price,,  iv  cloth,  $6.00; 

leather .  .      $7.00 

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constitutes  one  of  their  chief  values  :  they  are  all  essentially  and  thoroughly  practical.  Dr, 
Tanner  never,  for  one  moment,  allows  this  utilitarian  end  to  escape  his  mental  view.  He 
aims  at  teaching  how  to  recognize  and  how  to  cure  disease,  and  in  this  he  is  thoroughly  suc- 
cessful. ...  It  is,'  indeed,  a  wonderful  mine  of  knowledge. — Medical  Times. 

SAME  AUTHOR. 

A  PRACTICAL  TREATISE  ON  THE  DISEASES  OF  IN- 
FANCY AND  CHILDHOOD.  Third  American  from  the  last  Lon- 
don Edition,  Revised  and  Enlarged.  By  ALFRED  MEADOWS,  M.D., 
London,  M.R.C.P.,  Physician  to  the  Hospital  for  Women  and  to  the 
General  Lying-in  Hospital,  &c.,  &c.  Price  ....  $3.50 

This  book  of  Dr.  Tanner's  has  been  much  enlarged  and  the  plan  altered  by  Dr.  Meadows. 
As  it  now  stands,  it  is  probably  one  of  the  most  complete  in  our  language.  It  no  longer 
deals  with  children's  diseases  only,  but  includes  the  peculiar  conditions  of  childhood,  both 
normal  and  abnormal,  as  well  as  the  therapeutics  specially  applicable  to  that  class  of  patients. 
The  articles  on  Skin  Diseases  have  been  revised  by  Dr.  Tilbury  Fox,  and  those  on  Disc 


The  articles  on  Skin  Diseases  have  been  revised  by  Dr.  Tilbury  Fc 

of  the  Eye  by  Dr.  Brudenell  Carter,  both  gentlemen  distinguished  in  these  specialties.  — 

Medical  Times  and  Gazette. 

A  MEMORANDA  OF  POISONS.     A    New  and  much  Enlarged 
Edition.     Price .75 

TYSON  (JAMES),  M.D., 

Lecturer  on  Microscopy  in  the  University  of.  Pennsylvania,  &c, 

THE  CELL  DOCTRINE.  Its  History  and  Present  State,  with  a 
Copious  Bibliography  of  the  Subject,  for  the  use  of  Students  of  Medi- 
cine and  Dentistry.  With  Colored  Plate,  and  numerous  Illustrations 
on  Wood.  Price $2.00 

BY  SAME  AUTHOR. 
A  PRACTICAL  GUIDE  TO  THE  EXAMINATION  OF  URINE. 

For  the  use  of  Physicians    and    Students.     With   a    Colored  Plate   and 
numerous  Illustrations  Engraved  on  Wood.    A  1 2mo  Volume.    Price,  $1.50 

TAFT  (JONATHAN),  D.D.S., 

Professor  of  Operative  Dentistry  in  the  Ohio  College,  &c, 

A  PRACTICAL   TREATISE  ON  OPERATIVE   DENTISTRY. 

Third  Edition,  thoroughly  Revised,  with  Additions,  and  fully  brought 
•      .up  to  the  Present  State  of  the  Science.     Containing  over  100  Illustra- 
tions.    Octavo.     Price,  in  cloth,  $4.25.     In  leather,       .         .     $4-75 
Professor  Taft  has  done  good  service  in  thus  embodying,  in  a  separate  volume,  a  compre- 
hensive view  of  operative  dentistry.     This  gentleman's  position  as  a  teacher  must  have  ren- 
dered him  familiar  with  the  most  recent  views  which  are  entertained  in  America  on  this 
matter,  while  his  extensive  experience  and  well-earned  reputation  in  practice  must  have 
rendered  him  a  competent  judge  of  their  merits.     AVe  willingly  commend  Professor  Taft's 
able  and  useful  work  to  the  profession.—  London  Dental  Review. 

3 


34 
TROUSSEAU  (A.), 

Professor  of  Clinical  Medicine  to  the  Faculty  of  Medicine,  Paris,  &c, 

LECTURES  ON  CLINICAL  MEDICINE.  Delivered  at  the  H&el 
Dieu,  Paris.  Translated  from  the  Third  Revised  and  Enlarged  Edition 
by  P.  VICTOR  BAZIRE,  M.D.,  London  and  Paris;  and  JOHN  ROSE  COR- 
MACK,  M.D.,  Edinburgh,  F.R.S.,  &c.  With  a  full  Index,  Table  of  Con- 
tents, &c.  Complete  in  Two  volumes,  royal  octavo,  bound  in  cloth. 

Price  $10.00;   in  leather $12.00 

Trousseau's  Lectures  have  attained  a  reputation  both  in  ISngland  and  this  country  far 
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medical  men  could  afford  to  purchase  the  expensive  edition  issued  by  the^ydenhani  Society, 
it  has  had  an  extensive  sale.  In  order,  however,  to  bring  the  work  within  the  reach  of  all 
the  profession,  the  publishers  now  issue  this  edition,  containing  all  the  lectures  as  contained 
in  the  five-volume  edition,  at  one-half  the  price".  The  London  Lancet,  in  speaking  of  the 
work,  says:  *;  Jt  treats  of  diseases  of  daily  occurrence  and  of -the  most  vital  interest  to  the 
practitioner.  And  we  should  think  any  medical  library  absurdly  incomplete  now  which  did 
not  have  alongside  of  Watson,  Graves,  and  Tanner,  the  '  Clinical  Medicine'  of  Trousseau." 
The  Sydenham  Society's  Edition  of  Trousseau  can  also  be  furnished  in  sets,  or  in  separate 
volumes,  as  follows :  Volumes  I.,  II.,  and  111.,  £5.00  each.  Volumes  IV.  and  V.,  $4.00  each. 

TILT  (EDWARD  JOHN),  M.D. 

THE  CHANGE  OF  LIFE  IN  HEALTH   AND    DISEASE.     A 

Practical  Treatise  on  the  Nervous  and  other  Affections  incidental  to 

Women  at    the  Decline  of  Life.     From  the  Third  London  Edition. 

Price     .         .         .         .         »         .         .»         .          .         .          .     $3.00 

The  work  is  rich  in  personal  experience  and  observation,  as  well  as  in  ready  and  sensible 

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should  be  without,  as  the  best  we  have  on  a  class  of  diseases  that  makes  a  constant  demand 

upon  our  care,  and  requires  very  judicious  management  on  the  part  of  the  practitioner. — 

London  Lancet. 

TOYNBEE  (j.),  F.R.S. 

ON  DISEASES  OF  THE  EAR.  Their  Nature,  Diagnosis,  and1 
Treatment.  A  new  London  Edition,  with  a  Supplement.  By  JAMES 
HINTON,  Aural  Surgeon  to  Guy's  Hospital,  &c.  And  numerous  Illus- 
trations. Octavo. $5-°o 

THOMPSON  (SIR  HENRY),  F.R.C.S.,  &c. 

ON  THE  PREVENTIVE  TREATMENT  OF  CALCULOUS 
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PRACTICAL  LITHOTOMY  AND  LITHOTRITY.  Second  Edi- 
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THORNTON  (w.  PUGIN),  M.  D. 

Surgeon  to  Hospital  for  Diseases  of  the  Throat,  &c, 

ON  TRACHEOTOMY,  Especially  in  Relation  to  Diseases  of  the 
Larynx  and  Trachea.  With  Photographic  and  other  Illustrations. 
Price $r-75 

THOROWGOOD  (JOHN  c,),  M.D., 

Lecturer  on  Materia  Medicaatthe  Middlesex  Hospital. 

THE  STUDENT'S  GUIDE  TO  MATERIA  MEDICA.  With 
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TYLER  SMITH  (w.),  M.D., 

Physician,  Accoucheur,  and  Lecturer  on  Midwifery,  &c, 

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GARDNER,  M.D.  With  Illustrations.  Octavo.  .  .  .  $5.00 


35 

THOROWGOOD  (j.  c.),  M.  D. 

Physician  to  the  City  of  London  Hospital  for  Diseases  of  the  Chest,  and  to  the  West  London  Hospital,  &c. 

NOTES  ON  ASTHMA.  Its  various  Forms,  their  Nature  and 
Treatment,  including  Hay  Asthma,  with  an  Appendix  of  Formulae,  &c. 
Second  Edition.  Price $i-75 

TOMES  (JOHN),  F.  R.  S. 

Late  Dental  Surgeon  to  the  Middlesex  and  Dental  Hospitals,  &c. 

A  SYSTEM  OF  DENTAL  SURGERY.  The  Second  Revised  and 
Enlarged  Edition,  by  CHARLES  S.  TOMES,  M.A.,  Lecturer  on  Dental 
Anatomy  and  Physiology,  and  Assistant  Dental  Surgeon  to  the  Dental 
Hospital  of  London.  With  263  Illustrations.  Price  .  .  $5.00 

This  book  has  been  for  some  time  out  of  print  in  this  country.  The  material  progress  made 
in  the  science  of  Dental  Surgery  since  its  first  publication  has  rendered  large  additions  and 
many  revisions  necessary  to  the  New  Edition  :  in  order  to  bring  it  fully  up  to  the  time;  this 
lias  been  done  without  increasing  the  size  of  the  book  more  than  possible.  Many  improve- 
ments, however,  will  be  found  added  to  the  Text,  and  some  Sixty  new  illustrations  are  in- 
corporated in  the  volume. 

TOMES  (c.s.),M.A. 

Lecturer  on  Anatomy  and  Physiology,  and  Assistant  Surgeon  to  the  Dental  Hospital  of  London, 

A  MANUAL  OF  DENTAL  ANATOMY,  HUMAN  AND  COM- 
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TRANSACTIONS  OF  THE  COLLEGE  OF  PHYSICIANS 
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Price,  per  volume,       .  .     $2.50 

TUKE  (DANIEL  H.),  M.  D. 

Associate  Author  of  "A  Manual  of  Psychological  Medicine,"  &c. 

ILLUSTRATIONS    OF   THE    INFLUENCE    OF    THE    MIND 

UPON  THE  BODY.     Octavo.     Price  .  .     $4.00 

The  author  shows  very  clearly  in  this  book  the  curative  influence  of  the  mind,  as  well  as 

its  effect  in  causing  disease,  and  the  use  of  the  imagination  and  emotions  as  therapeutic 

agents.     His  object'is  also  to  turn  to  the  use  of  legitimate  medicine  the  means  so  irequeutly 

employed  successfully  in  many  systems  of  quackery. 

TIBBITS  (HERBERT),  M.  D. 

Medical  Superintendent  of  the  National  Hospital  for  the  Paralyzed  and  Epileptic,  &c, 

A  HANDBOOK  OF  MEDICAL  ELECTRICITY.  With  Sixty- 
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The  author  of  this  volume  is  the  translator  of  Dnchenne's  great  work  on  "  Localised  Elec- 
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only  when,  but  in  EXPLICIT  AND  FULL  DETAIL,  how  to  use  Electricity  in  the  treatment  of 
disease,  and  to  make  the  practitioner  as  much  at  home  in  the  use  of  his  electrical  as  hia 
other  medical  instruments. 


36 
VIRCHOW  (RUDOLPHE), 

Professor,  University  of  Berlin, 

CELLULAR  PATHOLOGY.  Translated  from  the  Second  Edition, 
with  Notes  and  Emendations,  by  FRANK  CHANCE,  B.A.,  M.A.,  144 
Illustrations.  .  .  .  .  .  .  .  $5-°° 


VAN  DER  KOLK  (j.  L.  c.  SCHROEDER), 

THE  PATHOLOGY  AND  THERAPEUTICS  OF  MENTAL 
DISEASES.  Translated  by  Mr.  RUDALL,  F.R.C.S.  Octavo.  $3.00 

WARING  (EDWARD  JOHN),  F.R.C.S.,  F.L.S.,  &c,  &c. 

PRACTICAL  THERAPEUTICS.  Considered  chiefly  with  refer- 
ence to  Articles  of  the  Materia  Medica.  Third  American  from  the  last 
London  Edition.  Price,  in  cloth,  $5.00 ;  leather  .  .  $6.00 

There  are  many  features  in  Dr.  "NVaring's  Therapeutics  which  render  it  especially  valuable 
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found  in  it  not  contained  in  similar  works;  also  in  its  completeness,  the  convenience  of  its  ar- 
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contains  also  an  excellent  INDEX  OF  DISEASES,  with  a  list  of  the  medicines  applicable  as 
remedies,  and  a  full  INDEX  of  the  medicines  and  preparations  noticed  in  the  work. 


WYTHE  (JOSEPH  H),  A.M.,  M.D.,  &c. 

THE  PHYSICIAN'S  POCKET,  DOSE,  AND  SYMPTOM  BOOK. 

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atology, Outlines  of  General  Pathology  and  Therapeutics,  £c.  The 
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WILKS  AND  MOXON. 

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WILSON  (ERASMUS),  F.R.S. 

HEALTHY  SKIN.  A  Popular  Treatise  on  the  Skin  and  Hair,  their 
Preservation  and  Management.  Eighth  Edition.  Cloth.  .  $1.25 


37 
WILSON  (GEORGE),  M.  A.,  M.  D. 

Medical  Officer  to  the  Convict  Prison  at  Portsmouth, 

A  HANDBOOK  OF  HYGIENE  AND   SANITARY  SCIENCE. 

With  Engravings.  Second  Edition,  carefully  Revised.  Containing 
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WAGSTAFFE  (WILLIAM  WARWICK),  F.  R.  C.  S. 

Assistant-Surgeon  and  Lecturer  on  Anaton\y  at  St,  Thomas's  Hospital, 

THE  STUDENT'S  GUIDE  TO  HUMAN  OSTEOLOGY.  With 
Twenty-three  Lithographic  Plates  and  Sixty  Wood  Engravings.  i2mo. 
Cloth.  Price .  $3.50 

WARD  (STEPHEN  H.),  M.D.,  F.  R.  C,  P. 

Physician  to  the  Seaman's  Hospital,  &c,,  &c, 

ON  SOME  AFFECTIONS  OF  THE  LIVER  and  Intestinal  Canal; 

with  Remarks  on  Ague  and  its  Sequelae,  Scurvy,  Purpura,  &c. 

Price •  $3-°° 

"Dr.  Ward's  book  is  of  a  purely  practical  character,  embodying  the  author's  experience, 
from  his  long  connection  as  physician  to  the  Seaman's  Hospital.  His  accurate  description 
of  the  diseases  treated  will  amply  repay  the  reader."  —  Dublin  Medical  Journal. 


WILSON  (ERASMUS),  F.  R.  C.  S.,  &c. 

CONTAINING  THREE  HUNDRED  AND  SEVENTY-ONE  ILLUSTRATIONS. 

THE  ANATOMIST'S  VADE  MECUM.  A  Complete  System  of 
Human  Anatomy.  The  Ninth  Revised  and  Enlarged  London  Edition. 
Edited  and  fully  brought  to  the  Science  of  the  day  by  Prof.  GEORGE 
BUCHANAN,  Lecturer  on  Anatomy  in  Anderson's  University,  Glasgow, 
with  many  New  Illustrations,  prepared  expressly  for  this  Edition. 
Price  ......  ...  $5.50 

WEDL  (CARL),  M.  D. 

Professor  of  Histology,  &c.,  in  the  University  of  Vienna, 

DENTAL  PATHOLOGY.  The  Pathology  of  the  Teeth.  Witt 
Special  Reference  to  their  Anatomy  and  Physiology.  First  American 
Edition,  translated  by  W.  E.  BOARDMAN,  M.D.,  with  Notes  by  THOS. 
B.  HITCHCOCK,  M.D.,  Professor  of  Dental  Pathology  and  Therapeutics 
in  the  Dental  School  of  Harvard  University,  Cambridge.  With  105 
Illustrations.  .  .  .  Price,  in  Cloth,  $4.50 ;  Leather,  $5.50 

This  work  exhibits  laborious  research  and  medical  culture  of  no  ordinary  character.  It 
covers  the  entire  field  of  Anatomy,  Physiology,  and  Pathology  of  the  Teeth.  The  author, 
Prof.  Wedl,  hag  thoroughly  mastered  the  subject,  using  with  great  benefit  to  the  book  the 
very  valuable  material  left 'by  the  late  Dr.  Heider,  Professor  of  Dental  Pathology  in  the  Uni- 
versity of  Vienna,  the  result  of  the  life-long  work  of  this  eminent  man. 


38 

WOODMAN  AND  TIDY. 

A  HANDY-BOOK  OF  FORENSIC  MEDICINE  AND  TOXI- 
COLOGY. By  W.  BATHURST  WOODMAN,  M.  D.  St.  And.,  Assistant 
Physician  and  Lecturer  on  Physiology  at  the  London  Hospital ;  and  C. 
MEYMOTT  TIDY,  M.  A.,  M.  B.,  Lecturer  on  Chemistry,  and  Professor  of 
Medical  Jurisprudence  and  Public  Health,  at  the  London  Hospital. 
With  Numerous  Illustrations.  Preparing. 

WELLS  (j.  SCELBERG), 

Ophthalmic  Surgeon  to  King's  College  Hospital,  &c. 

TREATISE  ON  THE  DISEASES  OF  THE  EYE.  Illustrated  by 
Ophthalmoscopic  Plates  and  numerous  Engravings  on  Wood.  The 
Third  London  Edition.  Cloth,  $5.00;  leather  .  .  .  $6.00 

This  is  the  author's  own  edition,  printed  in  London  under  his  supervision,  and  issued  in 
this  country  by  special  arrangement  with  him. 

SAME  AUTHOR. 

ON  LONG,  SHORT,  AND  WEAK  SIGHT,  and  their  Treatment 
by  the  Scientific  Use  of  Spectacles.  Third  Edition  Revised,  with  Ad- 
ditions and  numerous  Illustrations.  Price  ....  $3.00 

WRIGHT  (HENRY  G.),  M.D., 

Member  of  the  Royal  College  cf  Physicians,  &c. 

ON  HEADACHES.  Their  Causes  and  their  Cure.  From  the  Fourth 
London  Edition.  i2mo.  Cloth.  .  .  .  .  .  $1.25 

The  author's  plan  is  simple  and  practical.  He  treats  of  headaches  in  childhood  and  youth, 
in  adult  life  and  old  age,  giving  in  each  their  varieties  and  symptoms,  and  their  causes  and 
treatment.  It  is  a  most  satisfactory  monograph,  as  the  mere  fact  that  this  is  a  reprint  of  the 
fourth  edition  testifies. 

WALTON  (HAYNES), 

Surgeon  in  Charge  of  the  Ophthalmic  Department  of,  and  Lecturer  on  Ophthalmic  Medicine  and  Surgery 

in,  St.  Mary's  Hospital. 

A  PRACTICAL  TREATISE  ON  DISEASES  OF  THE  EYE, 
Third  Edition.  Rewritten  and  enlarged.  With  five  plain,'  and  three 
colored  full-page  plates,  numerous  Illustrations  on  Wood,  Test  Types, 
&c.,  &c.  Octavo  volume  of  nearly  1200  pages.  Price  $9-°° 

WATERS  (A.  T.  H.),  M.D.,  F.R.C.P.,  &c. 

DISEASES  OF  THE  CHEST.  Contributions  to  their  Clinical  His- 
tory, Pathology,  and  Treatment.  Second  Edition,  Revised  and  Enlarged. 
With  numerous  Illustrative  Cases  and  Chapters  on  Haemoptysis,  Hay 
Fever,  Thoracic  Aneurism,  and  the  Use  of  Chloral  in  certain  Diseases 
of  the  Chest,  and  Plates.  Octavo.  Price  .  .  .  .  $5.00 

WALKER  (ALEXANDER), 

Author  of  "  Woman,"  "  Beauty,"  &c, 

INTERMARRIAGE;  or,  the  Mode  in  which,  and  the  Causes  why, 
Beauty,  Health,  Intellect  result  from  certain  Unions,  arid  Deformity, 
Disease,  and  Insanity  from  others.  With  Illustrations.  i2mo.  $1.50 


It  is  eminently  a  book  which  will  teach  the  Student. — Practitioner. 
It  forms  one  of  the  most   convenient,  practical,  and  concise  books  yet 
published  on  the  subject.  —  London  Lancet. 

MEADOWS'  MANUAL  OF  OBSTETRICS. 
THE  TEIKD  REVISED  ATO  ENLAEGED  EDITION,  NOW  EEADY, 

WITH  ONE  HUNDRED  AND  FORTY-FIVE  ILLUSTRATIONS. 

INCLUDING   THE    SIGNS    AND    SYMPTOMS    OF    PREGNANCY, 

Obstetric  Operations,  Diseases  of  the  Puerperal  State,  &c.,  &c.  By 
ALFRED  MEADOWS,  M.  D.,  Physician  to  the  Hospital  for  Women,  to 
the  General  Lying-in  Hospital,  &c.,  &c.  Second  American  from  the 
Third  London  edition.  With  numerous  Illustrations.  Price  .  $3.25 

In  this  new  edition, ..  .not  merely  is  the  practical  treatment  of  Labor,  and  also  of  the  Dis- 
eases an.d  Accidents  of  Pregnancy,  well  and  clearly  taught,  but  the  anatomical  machinery 
of  parturition  is  more  effectively  explained  than  in  any  other  treatise  that  we  remember; 
besides  this,  the  book  is  honorably  distinguished  among  manuals  of  Midwifery  by  the  ful- 
ness with  which  it  goes  into  the  subject  of  the  structure  and  development  of  the  ovum.  On 
all  questions  of  treatment,  whether  by  medicines,  by  hygienic  regimen,  or  by  mechanical  or 
operative  appliances,  this  treatise  is  as  satisfactory  as  a  work  of  manual  size  could  be ;  students 
and  practitioners  can  hardly  do  better  than  adopt  it  as  their  vade-mecum. — The  Practitioner. 

Upwards  of  ninety  new  engravings  have  been  inserted  in  this  edition,  and,  with  a  view  to 
facilitate  reference,  the  author  has  furnished  it  with  a  very  full  and  complete  table  of  contents 
and  inlex.  We  can  cordially  recommend  this  manual  as  accurate  and  practical,  and  as  con- 
taining in  a  small  compass  a  large  amount  of  the  kind  of  information  suitable  alike  to  the 
student  and  practitioner.—  London  Lancet. 

It  is  concise,  well  arranged,  and  remarkably  complete,  as  a  guide  to  the  student  during  his 
lecture  term ;  and  as  a  ready  reference  to  the  Physician,  no  work  of  similar  character  equals 
it  in  value. — Buffalo  Medical  Journal. 

The  systematic  arrangement  of  subjects,  and  the  concise,  practical  style  in  which  it  is 
written,  make  the  work  especially  valuable  as  a  student's  manual,  while  a  very  full  table 
of  contents  and  index  renders  it  easily  accessible  as  a  work  of  reference. — Chicago  Medical 
Examiner. 

There  can  be  no  doubt  that  this  manual  will  be  generally  accepted  as  a  brief,  convenient,' 
and  compendious  guide  to  the  study  and  practice  of  the  Obstetric  Art. — Richmond  and 
Louisville  Medical  Journal. 

We  cannot  but  feel  that  every  teacher  of  obstetrics  has  good  cause  to  congratulate  himself 
on  being  able  to  put  in  the  hands  of  the  student  a  book  which  contains  so  rnuoii  valuable 
and  reliable  information  in  so  condensed  a  form. — Philadelphia  Medical  Times. 

It  is  concisely  and  clearly  written,  and  the  information  is  on  the  whole  on  a  level  with  the 
most  recent  knowledge  of  the  day. — British  and  foreign  Medical  Review. 

A  work  which  embodies  a  larger  amount  of  practical  information  than  any  other  book  on 
the  subject. — Pacific  Medical  and  Surgical  Journal. 

It  is  with  great  gratification  that  we  are  enabled  to  class  Dr.  Meadows'  Manual  as  a  rare 
exception,  and  to  pronounce  it  an  accurate,  practical,  and  creditable  work,  and  to  unhesi- 
tatingly recommend  it  to  both  student  and  practitioner.' — American  Journal  of  Obstetrics. 

It  is  a  book  of  decided  merit :  every  page  teems  with  sound,  practical  common  sense,  advice 
and  suggestions. — Kansas  City  Medical  Journal. 


ROBERTS'  PRACTICE  OF  MEDICINE 

A  New  Enlarged  Edition, 

JUST  READY. 

Uniformly  commended  by  the  Profession  and  the  Press. 

A  HAND-BOOK  OF  THE  THEORY  AND  PRACTICE  OF  MEDI- 
CINE.    By  FREDERICK  T.  ROBERTS,  M.D.,  M.R.C.P.,  Assistant  Pro- 
fessor and  Teacher  of  Clinical  Medicine  in  University  College  Hospital, 
Assistant  Physician  in  Brompton  Consumptive  Hospital,  &c.,  &c. 
Second  Edition.     Octavo.     Price,  in  cloth          ....       $5.00 

leather       ....         6.00 

The  Publishers  are  in  receipt  of  numerous  letters  from  Professors  in  the  various  Med- 
ical Schools,  uniformly  commending  this  book ;  whilst  the  following  extracts  from  the 
Medical  Press,  both  English  and  American,  fully  attest  its  superiority  and  great  value 
not  only  to  the  student,  but  also  to  the  busy  practitioner. 

This  is  a  good  book,  yea,  a  very  good  book.  It  is  not  so  full  in  its  Pathology  as  "  Aitken," 
so  charming  in  its  composition  as  "  Watson,"  nor  so  decisive  in  its  treatment  as  "  Tanner; " 
but  it  is  more  compendious  than  any  of  them,  and  therefore  more  useful.  We  know  of  no 
other  work  in  the  English  language,  or  in  any  other,  for  that  matter,  which  competes  with 
this  one.  — Edinburgh  Medical  Journal. 

We  have  much  pleasure  in  expressing  our  sense  of  the  author's  conscientious  anxiety  to 
make  his  work  a  faithful  representation  of  modern  medical  beliefs  and  practice.  In  this  he 
has  succeeded  in  a  degree  that  will  earn  the  gratitude  of  very  many  students  and  practition- 
ers: it  is  a  remarkable  evidence  of  industry,  experience,. and  research.  —  Practitioner. 

That  Dr.  Roberta's  book  is  admirably  fitted  to  supply  the  want  of  a  good  hand-book  of 
medicine,  so  much  felt  by  every  medical  student,  does  not  admit  of  a  question.  —  Students1 
Journal  and  Hospital  Gazette. 

Dr.  Roberts  has  accomplished  his  task  in  a  satisfactory  manner,  and  has  produced  a  work 
mainly  intended  for  students  that  will  be  cordially  welcomed  by  them ;  most  of  the  observa- 
tions on  treatment  are  carefully  written  and  worthy  of  attentive  study ;  the  arrangement  is 
good,  and  the  style  clear  and  simple.  —  London  Lancet. 

It  contains  a  vast  deal  of  capital  instruction  for  the  student,  much  valuable  matter  in  it  to 
commend,  and  merit  enough  to  insure  for  it  a  rapid  sale. — London  Medical  Times  and  Gazette. 

There  are  great  excellencies  in  this  book,  which  will  make  it  a  favorite  both  with  the 
accurate  student  and  busy  practitioner.  The  author  has  had  ample  experience. — Richmond 
and  Louisville  Journal. 

We  confess  ourselves  most  favorably  impressed  with  this  work.  The  author  has  performed 
his  task  most  creditably,  and  we  cordially  recommend  the  book  to  our  readers.  —  Canada 
Medical  and  Surgical  Journal. 

A  careful  reading  of  the  book  has  led  us  to  believe  that  the  author  has  written  a  work 
more  nearly  up  to  the  times  than  any  -that  we  have  seen  ;  to  the  student,  it  will  be  a  gift  of 
priceless  value.  —  Detroit  Review  of  Medicine. 

Our  opinion  of  it  is  one  of  almost  unqualified  praise.  The  style  is  clear,  and  the  amount  of 
useful  and,  indeed,  indispensable  information  which  it  contains  is  marvellous.  We  heartily 
recommend  it  to  students,  teachers,  and  practitioners.  — Boston  Med.  and  Surgical  Journal. 

It  is  of  a  much  higher  order  than  the  usual  compilations  and  abstracts  placed  in  the  hands 
of  students.  It  embraces  many  suggestions  and  hints  from  a  carefully  compiled  hospital 
experience ;  the  style  is  clear  and  concise,  and  the  plan  of  the  work  very  judicious. — Medical 
and  Surgical  Reporter. 

It  is  unsurpassed  by  any  work  that  has  fallen  into  our  hands  as  a  compendium  for  students 
preparing  for  examination.  It  is  thoroughly  practical  and  fully  up  to  the  times.— The  Clinic. 

We  find  it  an  admirable  book.  Indeed,  we  know  of  no  hand-book  on  the  subject  just  now 
to  be  preferred  to  it.  We  particularly  commend  it  to  students  about  to  enter  upon  the 
practice  of  their  profession.  —  St.  Louis  Medical  and  Surgical  Journal. 

If  there  is  a  book  in  the  whole  of  medical  literature  in  which  so  much  is  said  in  so 
few  words,  it  has  never  come  within  our  reach.  So  clear,  terse,  and  pointed  is  the  style  ; 
so  accurate  the  diction,  and  so  varied  the  matter  of  this  book,  that  it  is  almost  a  dictionary 
of  practical  medicine.  —  Chicago  Medical  Journal. 

The  author's  style  is  clear,  concise,  and  methodical.— Chicago  Medical  Examiner. 

Dr.  Roberts  has  given  us  a  work  of  real  value,  and  especially  for  the  use  of  students  is 
the  book  a  good  one.  —  Lancet  and  Observer. 


14  DAY  USE. 

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